Chemistry I
Attachments
Attachment A
CLE: 1.1.A.b, d
Properties of Metals and Nonmetals
Objectives:
Students will:
1. Understand that every element is classified as a metal, nonmetal or se mimetal (metalloid) based on its
individual properties.
2. Be able to classify an element as a metal, nonmetal or semimetal based on experimental observations of
physical and chemical properties.
Materials:
• Eight labels
• Seven vials with caps, filled with the following:
- Iron filings
- Sulfur rolls
- Mossy zinc
- Graphite (replacement leads for mechanical pencils work well)
- Silicon
- Mossy tin
- Carbon
(If the above materials are not available, some substitutes are: paper clips, beebees, nails, fishing
weights, charcoal)
• One dropper bottle
• 6M hydrochloric acid
• One hammer
• Eight pieces of paper each measuring approximately 3.5 × 5 inches
• A conductivity apparatus such as 9-volt battery, a small appliance light bulb, and three pieces of
insulated copper wire to make an open circuit (the circuit will be closed with each of the seven
samples)
• One test tube holder
• Seven test tubes
• Every student should have the follow ing:
- Safety goggles
- A copy of the Properties Data Sheet handout (see attached)
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Attachment A
CLE: 1.1.A.b, d
Procedures:
1.
Before beginning this activity, students should already have a basic understanding of the
differences in the physical properties of luster, malleability, and conductivity between metals and
nonmetals. Students should understand that metalloids have characteristics of bot h metals and
nonmetals and that acids will react with most metals and not nonmetals. Students should always
be reminded to follow proper safety procedures and guidelines when working with any chemicals.
2.
Break the class into groups of two or three, depending on class size. Use labels to number a set
of vials from 1 through 7. Each group should receive a set of seven vials. Fill and label the
complete set of vials as follows:
Vial 1—iron filings
Vial 2—sulfur
Vial 3—mossy zinc
Vial 4—graphite
Vial 5—silicon
Vial 6—mossy tin
Vial 7—carbon
3.
Make a 6M solution of hydrochloric acid. Label a set of dropper bottles and fill with the acid
solution. There should be one dropper bottle of acid per group. At each group’s lab station place a
hammer, eight pieces of white paper, a set of vials containing samples 1-7, a dropper bottle of
6M hydrochloric acid, a conductivity apparatus, a test tube holder, and seven test tubes.
4.
5.
Give each student a copy of the Properties Data Sheet (see attached)
6.
Next, have one student in each group place a second piece of paper over the top of the sample
and crush the sample with the hammer. The student should then remove the top piece of paper
and each student in the group should observe the sample and record his or her observations in
the “malleability” column of the data sheet.
7.
Have one student within each group test the conductivity of the sample w ith the conductivity
apparatus by placing the ends of the wires not attached to the power source or light bulb into the
sample vial. DO NOT LET THE WIRES TOUCH EACH OTHER. Each student should observe the light
bulb and record his or her observations in the “conductivity” column of the data sheet.
8.
Have one student place a test tube in the test tube rack. The student should then pour sample 1
from the paper into the test tube and add 10 to 20 drops of 6M hydrochloric acid. Each student
should then wait at least three minutes before observing and then record his or her observations
in the “reaction with acid” column of the data sheet.
Before students begin their experiment, make sure they are all wearing their safety goggles.
Instruct a student in each group to take a piece of white paper, fold it in half, open it, and place it
on the lab top. Another member of the group should then open vial 1 and shake abo ut a peasized portion of the sample onto the white paper. Each student should observe the appearance of
the sample and record his or her observations in the “color” and “luster” columns of the data
sheet.
9. Each group should then repeat steps 3 through 7 above for the remaining six vial samples.
10. Each student, based on his or her group’s experimental observations and the know ledge he or
she has about the properties of metals and nonmetals, should then classify each of the samples
as a metal, no nmetal, or semimetal. He or she should record the answer in the “classification”
column of the data sheet. Each student should then submit his or her data sheet.
11.
After submission of the data sheets, discuss with the class their conclusions for each of th e
seven vials. What conclusions did they draw and why?
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Attachment A
CLE: 1.1.A.b, d
Properties of Metals and Nonmetals
Data Worksheet
Name: _____________________________________________ Date: _____________________
Group Members: _________________________________________________________________________
In this activity you will explore the properties of metals, nonmetals, and semimetals. You will be checking
the physical properties of color, luster, malleability, and conductivity, as well as, how the materials reacts with
acid. Be sure to make careful and complete observations. You will record your observations in the spaces
provided in the table below. At the end of the activity you will be required to classify each of your samples as
metal, nonmetal, or semimetal.
Sample
Number
Color
Luster
Malleability Conductivity
1
2
3
4
5
6
7
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Reaction Classification
With Acid
Attachment A
CLE: 1.1.A.b, d
Discussion Questions:
1. What accounts for the observed differences between samples?
Describe how these samples might
be arranged w ith respect to other elements in the periodic table. What other tests could be
performed to help identify materials as metals, nonmetals, and semimetals? What are some
useful applications of such tests?
2.
Our society is rapidly consuming raw materials that are nonrenewable. Discuss whether we
should rely on materials scientists to develop new materials to replace older ones that are no
longer available or consume and discard currently available materials more wisely. Is every
material replaceable?
3.
Discuss what types of materials are most important to recycle. Debate whether recycling should
be made the law nationw ide. Is the expense of enforc ing such a law justif ied or is the money
better spent on other social or scientific programs?
4.
Given the high quality and ready availability of substitutes, debate whether rare materials such as
gold or diamonds should be used for jewelry and art or saved s olely for technology and industry.
5.
Discuss how our global society would change if the technology to change one element into a
different element were developed. Is this a technology that, if developed, should be made public?
6.
One area of great advancement in materials science is the area of medicine. Artificial joints are
available, and scientists are currently developing artificial skin and blood. Discuss whether there
should be limits placed on the development of physiological substitutes. Can you think of any
reasons why advances in this area should be controlled?
7.
Many of the greatest advances in materials science have been made accidentally. In light of this,
discuss the value of following the scientific method versus chance. Is there ever room for chance
when strictly adhering to the scientific method?
Evaluation:
The data sheet for this activity can be used as the evaluation. Each of the observations in the color, luster,
malleability and conductivity columns can be assigned a value of one point. Each classification can be
assigned a value of three points. The total points for this activity are then 49, which can be rounded to 50.
The column for reaction with acid is not graded because the bubbles of gas are sometimes very difficult to
observe. Evaluation of the classification should be done based on the student observations, not necessarily
on what the sample actually is. The reason is that the students are to classify based on their own
experimental data, which may or may not be correct.
Extensions:
Evaluating Electrolytes
Metals are not the only substances that conduct electricity. Electrolytes also conduct electricity and are
essential to the proper functioning of our bodies. Discuss with students what an electrolyte is. Have
students use a conductivity apparatus to investigate the following solutions and determine if they are a
strong electrolyte, weak electrolyte, or nonelectrolyte. The solutions are salt water, sugar water, rubbing
alcohol, tap water, and distilled water. Have them make a prediction based on the chemical formula of the
solution and then check their hypothesis. Once they have checked these solutions, they may want to test
bottled spring water or a few sports drinks to see if they are strong electrolytes, weak electrolytes, or
nonelectrolytes.
NOTE: Make all solutions with bottled distilled water since tap water and even some deionized water can
test as weak electrolytes.
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Attachment B
CLE: 1.1.A.c
Name _________________________________
Part I. Classify each of the following substances as; an element, a compound, a solution, or a
heterogeneous mixture.
1. Sand
2. Salt
3. Pure Water
4. Soil
5. Soda
6. Pure A ir
7. Carbon Dio xide
8. Go ld
9. Bronze
10. Oxygen
11. Salad Dressing
12. Salt Water
Part II. In the spaces provided, describe the distinguishing characteristics of the major categories of matter.
13. Element -
14. Co mpound -
15. Solution -
16. M ixture -
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Attachment B
CLE: 1.1.A.c
Answers to Worksheet
Answers - part I.
1) mixture
2) compound
3) compound
4) mixture
5) solution
6) solution
7) compound
8) element
9) solution
10) element
11) mixture
12) solution
Part II – Answers will vary
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Attachment C
CLE: 1.1.A.c
Quiz on Atoms, Elements, Compounds, and Mixtures
Name ________________________________________ Date _____________________
1.
Given the STATEMENT about ...., decide whether it is TRUE or FALSE for an ELEMENT,
COMPOUND or MIXTURE
STATEMENT about ....
ELEMENT
COMPOUND MIXTURE
always has the same composition? true or false? true or false?
o
o
o
o
A.
B.
C.
D.
true or false?
false, false, true
true, true, false
false, true, true
true, false, false
2. Which of these is a compound?
o
o
o
o
A.
B.
C.
D.
CO2
Co
F2
P4
3. Which order of the three words matches the three substances salt, sodium, seawater ?
o
o
o
o
A.
B.
C.
D.
compound, element, mixture
mixture, compound, element
element, compound, mixture
element, mixture, compound
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Attachment C
CLE: 1.1.A.c
Name ________________________________________
4.
Silvery iron filings are added to yellow sulphur powder in a test tube. The contents of the test tube were
strongly heated until they glowed red without further heating to form a dark gray dull solid.
Which statement is TRUE about the contents of the test tube in the experiment?
o
o
o
o
A.
B.
C.
D.
at the end they are a mixture
at the start they can be separated with a magnet
at the start they are a compound
at the end they can be separated with a magnet
5. Which particle is formed whe n two different colorless gases chemically combine?
o
o
o
o
A.
B.
C.
D.
6
7
4
2
6. When some salt is dissolved in plenty of water, which statement is most likely true about the resulting
solution?
o
o
o
o
A.
B.
C.
D.
the solution becomes less concentrated the longer it is boiled
the boiling point increases the longer the solution is boiled
the freezing point is higher than pure water
the boiling point is lower than pure water
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Attachment C
CLE: 1.1.A.c
Name ________________________________________
7. The formula for copper sulphate is CuSo4 .
What is the ratio of Cu : S : O atoms in the formula?
o
o
o
o
A.
B.
C.
D.
4:3 :4
4:4 :4
1:4 :4
1:1 :4
8. Which of these is an element?
o
o
o
o
A.
B.
C.
D.
carbon monoxide
gasoline
nitrogen
water
9. Which statement is usually true when comparing the physical properties of metallic and non- metallic
elements?
o
o
o
o
A.
B.
C.
D.
metals have low melting and boiling points
non-metals are good conductors of electricity
non-metals have high densities
metals are good conductors of heat
10. Which order of the three words matches the three substances hydrogen, gasoline, wate r?
o
o
o
o
A.
B.
C.
D.
compound, element, mixture
element, mixture, compound
element, compound, mixture
mixture, compound, element
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Attachment C
CLE: 1.1.A.c
Answers to Quiz
1. B
2. A
3. A
4. B
5. C
6. B
7. D
8. C
9. D
10. B
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Attachment D
CLE: 1.1.B.a-c
Page 1
Unit-Solutions
Curriculum Guidelines: 20 hours
The purpose of this unit is to provide students with opportunities to become familiar with a variety of
chemical solutions, common units of concentration, methods of handling and preparing solutions and the
carrying-out of an acid-base titration.
I have broken it down into 7 main topics: Introduction to solutions, Solubility and Miscibility, Factors
affecting solubility, Water-the universal solvent?, Concentration and Dilution, Reactions in solutions, Acids
and Bases. If time permits a lesson on suspensions and colloids could be added.
Lesson 1 Introduction to Solutions 3 periods
We deal with chemical solutions in our everyday lives. It is important to understand the characteristics,
principles and properties of solutions, in some cases it is a matter of life and death. In our homes as well as in
the chemistry lab many substances are easier to store in solution form. What are some examples of solutions
that we find in our homes? As is the case with example x (from previous question) could be fatal if the labels
on these substances were misinterpreted since they give vital information, concentration, ingredients,
warnings, instructions, etc.. In many cases these substance are kept in a concentrated from and we must dilute
them in order to use the chemical safely and properly.
Characteristics of Solutions
A. Demonstration: either Dare to be Dense or Spheres of Oil compare with mixing vinegar and water (two
different colors) see attached to end of unit.
*Which of these is a solution?
*Why are the others not?
*What is one of the characteristics of a solution? Homogenous versus heterogeneous.
*Has anybody ever come across these terms before?
*In what sense/capacity/situation?
Define both terms.
Solutions are homogeneous because they are uniform throughout.
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Attachment D
CLE: 1.1.B.a-c
Page 2
B. Solute versus Solvent
Define:Dissolve-the molecules of one substance move into the spaces between the molecules of the other
substance
Solute-the substance that has lesser quantity and is being dissolved, is moving into the spaces.
Solvent-the substance of greater quantity, the one with the spaces between the molecules that need to
be filled.
Example Making instant Coffee.
*Which is the solute? Which is solvent?
*If sugar is added is it a solute or solvent?
Lab Tasty Solution see attached at end of unit
*What are the solute and solvent in this experiment?
*Account for the differences in the results of three parts.
*What affects the rate of a substance being dissolved?
*What was the effect of chewing on the candy?
C. Phases of Solutions
Both the solute and solvent can be in any phase.
*Let's think of examples for each of the following:
Solute Solvent Example
solid liquid coffee, ice packs, Kool-Aid
liquid liquid vinegar in water
gas liquid pop
gas gas air (O2 in N2) scuba tank (O2 in He)
liquid solid fillings (liquid Hg in Ag, Sn or Cu)
solid solid alloy-steel (Fe in one or more other elements) Jewelry (Cu in Au)
Have examples present of them. Or have them develop their own chart from the examples.
*Let's classify each of these examples based on the phase of the solute and solvent.
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Attachment D
CLE: 1.1.B.a-c
Page 3
Lesson 2 Solubility and Miscibility 2 periods
*Have examples from previous day available to use again to illustrate this lesson
*Use these to ask questions so students have a hand in developing the lesson and definitions
Recap lesson 1.
Not all mixture become solutions. What are some examples of two substances being mixed that do not result
in a solution?
Depending on the phase of the solute the mixing of the two is referred to as either solubility or miscibility.
Solubility
A. Define solubility-the mass of a solute (solid or gas) that will dissolve in a given volume or mass of
solvent.
B. Spectrum of Solubility.
-very qualitative
-even the least soluble solid dissolve some molecules into water
-glass used in labs because it has such a low solubility in water
--Soluble versus Insoluble
Even though we just said that almost everything is soluble to some extent in a substance if the amount is not
large enough it is said to be Insoluble.
--Unsaturated solution
-all of the solute is dissolved
-that volume of solvent could hold more solute at those conditions
--Saturated solution
-maximum amount of solute that volume of solvent can dissolve at those conditions
-undissolved solute still visible
Supersaturated solution-Demo
-if heat saturated solvent and add more solute-What happens?
-more solute dissolved-Why?
-if cooled to original temperature and the solute remains in solution=supersaturated solution
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Attachment D
CLE: 1.1.B.a-c
Page 4
Miscibility
A. Define miscibility-the degree to which one liquid can be dissolved into another.
B. Spectrum of Miscibility
-repeat spectrum of solubility
Miscible versus Immiscible
--Immiscible
-although spectrum says that all liquids are miscible to a certain degree we don't actually say that a liquid is
miscible if it does not mix very much.
--Partially miscible
-mixes to certain extent in certain proportions
--Miscible
-no apparent limit to the "solubility" of one liquid into another
-form solutions in any proportions
Lesson 3 Factors Affecting Solubility or Miscibility 2 periods
A. Lab-set up an experiment using different solvents and solutes at different temperatures and pressures if
possible
-be aware of any safety issues involving the heating or increasing the pressure of any of the chemicals
-this should help in your choice of chemicals
*Describe the results of each of the parts.
*What effect does heating or increasing pressure have?
*Give two examples of where knowing the information about the factors that affect solubility could help you.
B Note on factors affecting solubility or miscibility
-size, shape and charge of particles i.e. ionic, polar and nonpolar
like dissolves like
-temperature
-pressure *Henry's Law*
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Attachment D
CLE: 1.1.B.a-c
Page 5
Lesson 4 Water the Universal Solvent? 3 periods
A. Why is it called the universal solvent?-aqueous solutions
B. Shape of water molecules
C. Water dissolves ionic compounds eg.NaCl
D. Water dissolves polar compounds eg.HCl
E. Is it the universal solvent? Water and Nonpolar compounds
F. Discuss this factor and Acid Rain
G. Trip to water treatment plant
*What do they add to make water drinkable?
*Why are certain things added?
*Are they all soluble/miscible? What is the purpose of each being soluble or insoluble?
Lesson 5 Concentration and Dilution 4-5 periods
A. Define concentration, concentrated, diluted
B. Calculating Concentration C=n/v and n=m/M
C. Work time on concentration questions
D. Why dilute?
E. Calculate initial and final concentrations or volumes-since number of moles is constant n=Cv and ni=nf
then Civi=Cfvf
F. Work time dilution questions
G. Lab- have students prepare a standard solution of known concentration after doing calculations and make
dilutions of known concentration
H. Quiz or test on calculations
Lesson 6 Reactions in Solution 2 periods
A. Precipitation Reaction
B. Precipitation Lab
C. Neutralization Reaction
D. Writing ionic equations
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Attachment D
CLE: 1.1.B.a-c
Page 6
Demo-Dare to be Dense
Materials
-approximately equal amounts of glycerin, alcohol, water and vegetable oil (the amount depends on size of
jar)
-glass jar with screw lid (the tighter the better)
-food colouring
-3 small containers (to be used as mixing bowls)
Method
Pour the glycerin, alcohol, and water into the 3 respective containers (i.e. each mixing bowl has a different
liquid). Colour each of the three liquids a different colour being sure to mix the food colouring thoroughly ;
the oil will remain its natural colour. Slowly transfer the liquids into the glass jar in the following order:
glycerin, water, oil, alcohol. One may have to wait for the liquid to settle before adding the next layer. The
final product should be a glass jar having four distinct layers due to different densities.
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Attachment D
CLE: 1.1.B.a-c
Page 7
Demo-Spheres of oil
Purpose
To demonstrate that gravity has little effect on bodies submerged in a liquid.
Materials
-clear drinking glass
-1/2 cup rubbing alcohol
-1/2 cup water
-liquid cooking oil*regular works better than light*
-eye dropper
Procedure
Pour 1/2 cup water into glass tile glass slowly pour alcohol. DO NOT SHAKE. Fill eye dropper with cooking
oil. Place tip of dropper below surface of alcohol and add drops. *you can actually drop the oil from anywhere
and the results should be the same*
Results
The alcohol forms a layer on top of the water. The drops of oil form perfect spheres that float in the centre
below that alcohol and on top of the water.
Why?
Alcohol is lighter and will float on the water if the two are combined very carefully. Shaking causes them to
mix forming one solution. The oil is heavier than the alcohol but lighter than water; thus the oil drops float
between the two liquids.
Gravity does not affect the drops because they are surrounded by liquid molecules that are pulling equally on
them in all directions. The oil molecules pull on each other, forming a shape that takes up the least surface
area, a sphere.
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Attachment D
CLE: 1.1.B.a-c
Page 8
Lab-Tasty Solution
Purpose
To determine the fastest way to dissolve candy.
Material
3 pieces of soft candy *Certs Mints work well*
Procedure
Place one of the candies in your mouth. DO NOT chew and DO NOT move your tongue around. Record the
time it takes for this candy to dissolve. Place a second candy in your mouth . DO move the candy back and
forth with your tongue but DO NOT chew. Record the time it takes to dissolve this candy. Place the third
candy in your mouth. Do move it around and chew. Record the time to dissolve this third candy.
Results
Moving the candy around and chewing it decreased the time necessary for dissolving.
Why?
The candy dissolves in the saliva in your to form a liquid solution. Solutions contain two parts, a solute and a
solvent. The solvent is the saliva and the solute is the candy. The solute dissolves by spreading out evenly
throughout the solvent. The candy can quickly dissolve when it is crushed by chewing and stirred by moving
it around with the tongue.
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Attachment E
CLE: 1.1.B.a-c
Page 1
Name __________________________
Unit Test Solutions
1. Define any 5 of the following using examples to clarify when applicable.
solution:________________________________________________________________________________
_______________________________________________________________________________________
solute: __________________________________________________________________________________
________________________________________________________________________________________
solvent: _________________________________________________________________________________
________________________________________________________________________________________
dilution factor: ____________________________________________________________________________
________________________________________________________________________________________
homogeneous: ____________________________________________________________________________
________________________________________________________________________________________
soluble: _________________________________________________________________________________
________________________________________________________________________________________
miscible: ________________________________________________________________________________
________________________________________________________________________________________
concentration: ____________________________________________________________________________
________________________________________________________________________________________
precipitate:_______________________________________________________________________________
________________________________________________________________________________________
neutralization: ___________________________________________________________________________
________________________________________________________________________________________
2. Compare and contrast saturated, supersaturated and unsaturated. A table form could be used.
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Attachment E
CLE: 1.1.B.a-c
Page 2
Unit Test Solutions
3. Explain the process you would use to test a solution to see if it was unsaturated or supersaturated.
4. Using the observations from the lab and your notes explain the factors that affect solubility.
5. Why is water called the universal solvent? Is this name appropriate? Why or why not?
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Attachment E
CLE: 1.1.B.a-c
Page 3
6. Calculate the concentration in moles per Litre of each of the following aqueous solutions:
a) 1.06 g of sodium carbonate dissolved in 100.0 mL of solution
b) 111.1 g of calcium chloride dissolved in 20.0 L of solution
c) 5.85 g of sodium chloride in 5.0 L of water
7. For each of the following calculate the volume required to prepare each of the diluted so lutions:
a) Given 6.0M NaOH; need 5.0 L of 0.10M NaOH
b) Given 12M HNO3; need 250 mL of 0.20M HNO3
c) Given 2.0M HCl; need 0.50 L of 0.10M HCl
d) Given 1.0 MBaCl2; need 125 mL of 0.040M BaCl2
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Attachment F
CLE: 1.1.B.a-c
Page 1
Crystal Clear Chemistry
437
Attachment F
CLE: 1.1.B.aPage 2
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Attachment F
CLE: 1.1.B.aPage 3
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Attachment G
CLE: 1.1.F.c
Atomic Structure and Ionic Bonding (A Visual Approach)
Objectives:
The student will be able to:
1. Determine the number of protons, neutrons and electron for a given element by using the periodic
table.
2. Construct and draw models and diagrams of atoms.
3. Use the concept of the stable octet to predict simple molecular formulas.
4. Distinguish between elements and compounds.
Materials Needed:
4 boxes of round toothpicks (250 in box)
1/4 inch round blue self-adhesive labels
1/2 inch round green self-adhesive labels
1/2 inch round red self-adhesive labels
one bag large white marshmallows
three bags mini- marshmallows (these come in four colors)
one square sheet (at least 6 inches square) aluminum foil
one piece of white chalk
* These materials were used for a class size of 20. *
Strategy:
Use the aluminum foil and the white chalk to explain the difference between compounds and elements.
(For this demonstration we are assuming that the foil is made only of aluminum and the chalk is pure calcium
carbonate.) This can be done by utilizing the physical properties of these substances (for example: melting
point/ boiling point). Explain that the aluminum is made of similar atoms with similar properties and that the
chalk is made of different atoms (carbon, oxygen, calcium). If you separated these different atoms from the
chalk, they would have different properties. Since the aluminum is made of only one type of atom we call it
an element. It cannot be broken down into smaller pieces. The chalk can be broken down into smaller parts
or atoms. Therefore, it is called a compound.
After defining an element and an atom, describe the parts of the atom starting with the proton and neutron.
This should lead into an explanation of the atomic number and the mass number. Use the toothpicks, large
white marshmallows and mini- marshmallows to build a three-dimensional model of an atoms nucleus. The
large white marshmallow is used to hold the nucleus together. It should be explained that a real nucleus does
not have a different substance in its center but is composed of only protons and neutrons. The toothpicks are
inserted into the large white marshmallow so that two ends of the
toothpick are sticking out. The mini- marshmallows are then placed on the ends of the toothpick so two minimarshmallows may be added with one toothpick.
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Attachment G
CLE: 1.1.F.c
Students should choose only two colors of mini- marshmallows, one to represent protons and one to represent
neutrons. The toothpicks may also be broken in half to add only one mini- marshmallow to a vacant place on
the large white marshmallow. Use flashcards with the elements symbols (this will introduce the symbols used
for atoms) and have students select a nucleus to build. There should be only one symbol per flashcard (A
large marshmallow will hold approximately fifty mini- marshmallows.)
The self-adhesive labels are used to construct two-dimensional models of the entire atom. An explanation
of neutrality and placement of electrons must be given prior to this activity. Also, elements for this section
must be selected in pairs from elements 1 through 18 so that each pair, when bonded, has a total of eight
valence electrons. These elements will be used for bonding. Models will be constructed on paper with the red
and green circles in the center representing protons and neutrons and the smaller blue dots around the center or
nucleus representing electrons. It may be helpful to draw three concentriccircles on the paper to represent the
respective orbitals. This will help students place the electrons in the correct orbital.
When the two-dimensional models are finished, explain that atoms like to bond so that the total number of
outer electrons in the compound is equal to eight. Have students find a partner in the room to bond with so
that the total number of outer electrons forms this stable octet. This can lead into a discussion about the stable
octet and valence electrons. The number of valence electrons is also listed at the top of each group on the
periodic table. Let students discover this.
Performance Assessment:
Before the bonding activity, use the two-dimensional models to play a game. Hang the models on the
walls of the room and have students guess which atom each student constructed. Student should only have
their name on the model NOT THE ATOM'S NAME. Students should be able to list the number of protons,
neutrons and electrons to determine the element. When the game is finished you can see which students
constructed models correctly and which students were able to utilize their knowledge to "guess" or identify the
other atoms.
Conclusion:
In doing the activity, students will see trends in the periodic table that were not discussed. For example,
students may observe that the atomic nucleus gets larger as the mass number gets larger. They may also
discover that all the elements in a particular group have the same number of valence electrons.
Additionally, this activity could be used to inspire artistic creativity by allowing students to construct
models of atoms using materials that they choose and bring in from home. Students may also modify the
existing activity; for example, they may choose not to fasten the mini- marshmallows with toothpicks but may
want to try gluing the marshmallows together with rubber cement.
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Attachment H
CLE: 1.1.G.a
Title - Physical & Che mical Reactions
By - Charlotte McCoy
Primary Subject - Science
Secondary Subjects - Science
Grade Level - 5th - 8th grade
This lesson plan is the teachers side of a virtual classroom science lesson performed by the Discovery Center
of Springfield. To co-ordinate a virtual class or to inquire about our rates, contact us by phone (417) 8629910 ext. 713, or visit our website at www.discoverycenter.org/video_conferencing.asp.
I. Goals and Objectives:
Students will learn...
1. The difference between a physical reaction and a chemical reaction
2. The 4 ways in which a reaction can be sped up; (concentration, surface area, temperature, & catalysts).
II. Vocabulary:
1.
2.
3.
4.
5.
Physical Reaction: The matter stays the same, but change in size, shape, or appearance.
Chemical Reaction: The matter changes to a different kind of matter, or change in color.
Concentration: amount of substance dissolved in a certain amount of solvent.
Surface Area: refers to the amount of material that is exposed
Catalysts: substance that increases the rate of a chemical reaction without being changed by the
reaction.
6. Endothermic
7. Exothermic
III. Brain storm, "What is chemistry?"
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IV. PHYSICAL VS. CHEMICAL
"REACTIONS IN A BAG" EXPERIMENTS
EXPERIMENT #1:
MAKE YOUR OWN INSTANT COLD PACK (PHYSICAL)
The process in making the cold pack is not a chemical reaction but merely the physical act of dissolving.
When ammonium nitrate is dissolved in water, the process is endothermic, thus producing the cold pack.
You will need: Ammonium nitrate, tap water, ziplock bag (sandwich size), graduated cylinder
* Wear chemical resistant goggles, gloves and apron!
1. Weigh out 25 grams of ammonium nitrate directly into a one-quart size Ziplock plastic bag.
2. Using a graduated cylinder, measure out 50 mL of water.
3. Quickly, pour the water into the bag of ammonium nitrate, and seal the bag (try and remove excess air
before sealing the bag.)
4. Gently squeeze the bag to mix the solid and water.
5. Let the students feel the bag. It becomes cold within seconds and will remain cold for about 20 minutes.
EXPERIMENT #2:
CALCIUM CHLORIDE: A REACTION IN A BAG. (CHEMICAL)
Introduces students to a chemical reaction involving a color change, the formation of a gas and heat changes
from hot to cold. The students can actually hold this chemical reaction in their hands to see and feel the
reaction take place. The acid-base indicator will change colors (from basic to acidic). For example: phenol red
solution goes from red to orange to yellow. Universal indicator solution starts out green and changes to pink.
Cabbage juice, changes from blue- green to purple to pink. The plastic bag will also inflate due to the
formation of carbon dioxide gas.
You will need:calcium chloride, Sodium Bicarbonate (baking soda), Acid-Base indicator (any kind), Ziplock
sandwich bags, spoons, graduated cylinder
1. Place one spoonful of calcium chloride into a plastic sealable bag.
2. place 1 spoonful of sodium bicarbonate (BAKING SODA) into the bag. Seal the bag, shake it and see if a
chemical reaction takes place.
3. measure 10 ml (or 2 teaspoons) of indicator solution. Carefully add it to the bag. Flatten the bag to remove
the air and seal it.
4. Tilt the bag back-and- forth to wet all of the solid. Squeezing the bag may also help in wetting the solid. Be
careful not to squeeze the bag too hard as it might break or open up.
5. observe the reaction. If the bag gets tight due to pressure, open the seal to release the pressure, then reseal it.
6. Answer the following:
a.) How was this experiment different then the one before?
b.) Did a noticeable reaction occur before the indicator solution was added?
c.) What color change did the indicator go through?
d.) Why does the bag inflate?
e.) Does the reaction get hot or cold initially?
f.) Does the reaction get hot or cold after 1 minute?
g.) What observations did you make that tell you a chemical reaction is taking place?
h.) Was this experiment a physical or chemical reaction?
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V. Define and clarify the difference between a physical and chemical reaction.
VI. RATE OF CHEMICAL REACTIONS EXPERIMENTS
There are many ways to change the rate of a chemical reaction. It can either be sped up or slowed down. There
are 4 things that affect the rate of a chemical reaction:
1. Concentration
2. Surface Area
3. Catalysts
4. Temperature
EXPERIMENT #1:
Concentration of vinegar (Balloon Blowing)
You will need: ¼ cup vinegar, 2 tbsp baking soda, 2 balloons, 2 graduated cylinders.
1. Pour the vinegar into one of the graduated cylinders.
2. Pour watered down vinegar into the other graduated cylinder
3. Stretch open the balloon mouth and carefully pour the baking soda into both of the balloon.
4. Place the balloon mouth over both of the cylinders. Make sure that the balloon mouth is tightly around the
neck of the graduated cylinder.
5. Hold the balloon to the side so that the baking soda does not fall into the graduated cylinder.
6. Shake the balloon so that the baking soda falls into both of the graduated cylinders.
What happened? Which balloon blew up faster? More?
EXPERIMENT #2: Surface Area (Antacid Tablet Race)
You will need: Antacid Tablets, water, napkins, cups, spoons
1. Group students into groups of 2.
2. 1 partner crushes tablet with the spoon and puts the powder onto the spoon.
3. At the same time, partner #1 puts powder into cup A and the other partner puts tablet into the cup B.
4. Which tablet dissolves first?
Increasing surface area, speeds up the reaction.
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EXPERIMENT #3: Paper Clip Catalyst
You will need: paper cut in the size of a dollar, 2 large paper clips per student.
1. Give each student a strip of paper the size of a dollar.
2. Have them fold it into thirds, the shape of a Z or N.
3. Insert big ear of paper clip, clipping the second and third folds together.
4. Insert big ear of second paper clip, clipping the first and third folds together.
5. Grab the papers ends and pull
6. paper clips should come free of the paper but be hooked together.
A catalyst speeds up the reaction but does not become part of the reaction.
EXPERIMENT #4: Heat (Dry Ice Film Poppers)
You will need: dry ice chips, a film canister for each student.
1. Students must wear eye goggles.
2. Team students up to do a popper first without adding water.
3. Then add hot water to the canister and have them observe which is the quicker explosion.
EXPERIMENT: #5: Flaming Coffee Creamer
Have students decide which of the 4 things that speed up chemical reactions the following experiment
demonstrates.
1. Try and set a pile of coffee creamer on fire. What happens? Nothing.
2. Sprinkle the creamer above the match, and you will get huge flame s!
You increase the surface area by allowing oxygen to get all around the creamer particles.
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Attachment I
CLE: 1.1.I.a
Conservation of Mass
Description
Students observe a chemical reaction, determine that a gas has mass, and confirm the law of conservation of mass and
energy.
Materials
-Balance
-Erlynmeyer flask
-Weighing paper
-Spatula
-Graduated cylinder
-Baking soda
-Vinegar
-Balloon
Preparations
1. Discuss reaction types, mass, and conservation of mass and energy with the class prior to teaching this lesson.
2. Collect listed materials.
Procedures
KNOWLEDGE AND SKILLS:
Students:
-balance a chemical equation and understand that mass is conserved in all reactions
-understand that there are a variety of reaction types; in all cases mass is conserved
-know that matter may exist as a solid, liquid, or gas; all forms of matter have mass
-know that a balanced chemical reaction may be represented as symbols and numbers, and that while compounds may
change, mass will be conserved
-know that mass is not conserved in a nuclear reaction (fission, fusion); however, mass and energy are conserved
overall
PROCEDURES:
1. Divide students into groups of three or four.
2. Instruct students to collect the following materials: 2 flasks, spatula, graduated cylinder, balloon, a weighing scale for
student use, vinegar, and baking soda.
3. Have students label and accurately determine the mass of each flask, and the mass of the balloon.
4. Give students access to a weighing scale. Ask them to weigh 2 grams of baking soda and place the soda into flask
#1. Repeat the procedure for flask #2.
5. Have students measure 10 ml of vinegar and accurately determine its mass.
6. Instruct students to predict what the final mass would be if they combined the 2 grams of baking soda with the10 ml of
vinegar. Record predictions.
7. Have students combine the vinegar with the baking soda in flask #1 and swirl until the foaming stops.
8. Allow students to determine the combined mass of the flask, vinegar and baking soda. Ask t hem to compare these
numbers to their original predictions. (The true values will be less than the predicted because a gas is produc ed which
escapes into the atmosphere.)
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Attachment I
CLE: 1.1.I.a
9. Allow students to share results and to discuss possible explanations.
10. Have students repeat steps 4-7 again. This time, a balloon will be attached to the top of the flask as soon as the
vinegar is added. The flask will be swirled and observations will be recorded until the foaming stops.
11. Allow students to determine the mass of the balloon, flask, vinegar and baking soda, and to compare the mass to
the combined original masses of the balloon, flask, baking soda and vinegar.
12. Allow students to share results and discuss possible explanations.
This lab may be done with common fizzing antacids from the store. A similar reaction may be obs erved, and the
components of a seltzer tablet may be analyzed.
Assessments: See Student Sheet Attached
The following questions should be answered afte r successful completion of the lab:
1. What explanation accounts for the observation that the mass of the reactants and the mass of the products in reaction
#1 were not equal?
(answer: A gas is produced which escapes and is not weighed.)
2. What explanation accounts for the observation that the mass of the reactants and the mass of the products in reaction
#2 were equal?
(answer: The gas produced is collected and weighed.)
3. What gas may have been produced in this reaction?
(answer: Carbon dioxide may have been produced.)
4. What reaction type is illustrated in this lab?
(answer: Double displacement is illustrated.)
5. What law is obeyed in this lab?
(answer: Law of conservation of mass and energy is obeyed.)
The following questions may be used to asses student understanding:
1. Which of the following states of matter does not have a measurable mass?
a. solid
b. liquid
c. gas
d. none of the above
(answer d. All forms of matter have a measurable mass.)
2. Which of the following statements is true of a c hemical reaction?
a. Mass is converted int o energy.
b. Energy is converted into mass.
c. Mass and energy are conserved.
d. Mass and energy are not involved in chemic al reactions.
(answer c. Mass and energy are conserved in all chemical reactions.)
3. What do coefficients in a balanced equation represent ?
a. The conservation of compounds in a reaction.
b. The conservation of mass in a reaction.
c. The conservation of energy in a reaction.
d. The conservation of heat in a reaction.
(answer b. The coefficients in a balanced reaction repres ent the conservation of mass.)
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Attachment I
CLE: 1.1.I.a
In all reaction types, the law of conservation of mass and energy must be obeyed. This is best represented through a
series of symbols and numbers that demonstrates the conservation bet ween products and reactants.
The law of conservation of mass and energy may be demonstrated though the observation of the five simple reaction
types: combination or synthesis, decomposition, single displacement or singe r eplacement, double displac ement or
double replac ement, and combustion.
Mass is not conserved in nuclear reactions (fission,fusion). In these cases, a small amount of mass is converted int o
energy. For this reason, the law is written for mass and energy together, rat her than separately.
In this lab, vinegar (acetic acid) reacts with baking soda (sodium bicarbonat e) to produce carbon dioxide, water and
sodium acetate. The carbon dioxide may be captured in the balloon.
Extensions
Enhancement:
Percent composition may be determined by comparing the mass of the gas in the balloon to the mass of the starting
compound.
Stoichiometric connections may be made between the amounts of gas produced and the amounts of starting mat erials.
Limiting reactants may also be illustrat ed.
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Student Assessment
Attachment J
CLE: 1.1.I.a
Name __________________________________________________
1. What explanation accounts for the observation that the mass of the react ants and the mass of the products in reaction
#1 were not equal?
2. What explanation accounts for the observation that the mass of the reactants and the mass of the products in reaction
#2 were equal?
3. What gas may have been produced in this reaction?
4. What reaction type is illustrated in this lab?
5. What law is obeyed in this lab?
6. Which of the following states of matter does not have a measurable mass? ________
a.
b.
c.
d.
solid
liquid
gas
none of the above
2. Which of the following statements is true of a chemical reaction? __________
a. Mass is converted into energy.
b. Energy is converted into mass.
c. Mass and energy are conserved.
d. Mass and energy are not involved in chemical reactions.
3. What do coefficients in a balanced equation represent? __________
a. The conservation of compounds in a reaction.
b. The conservation of mass in a reaction.
c. The conservation of energy in a reaction.
d. The conservation of heat in a reaction.
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Attachment K
CLE: 1.2.D.a
Page 1
We All Scream for Ice Cream
Duration of Activity: 2 days
Description of Activity:
Students will learn the difference between exothermic and endothermic chemical reactions by labeling given
reactions as either exothermic or endothermic. Students will make ice cream and use the scientific method to
determine if the reaction is exothermic or endothermic.
Objectives:




Students will label chemical reactions as either endothermic or exothermic.
Students will use the scientific method to hypothesize an outcome, collect, record, and interpret data,
and analyze experimental results.
Students will determine if making ice cream is an exothermic or endothermic reaction.
Students will make a chart of the temperatures recorded during the experiment using Microsoft Excel
or other spreadsheet software.
Materials/Equipment:






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

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Ice Cream ingredients including milk, sugar, and vanilla flavo ring.
Salt
Ice
Plastic zipper bags, quart and gallon size (Freezer bags work best.)
Thermometers, one per group
Gloves or hand towels for each student
Microsoft Excel or other spreadsheet software
Handout 1: Exothermic or Endothermic? (see attached)
Handout 2: Ice Cream Recipe and Directions (see attached)
Handout 3: Heating Things Up With Ice Cream (see attached)
Prerequisites (skills or background needed):



The teacher should teach a lesson defining the basic types of chemical reactions prior to conducting
this experiment.
Basic knowledge of the Scientific Method
Basic knowledge of Microsoft Excel or other spreadsheet software
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Page 2
Procedure
Teacher Component: The teacher will
1. prepare for the lesson by using Handout 2: Ice Cream Recipe and Directions to measure milk, sugar,
and vanilla and place in zippered plastic bags before class.
2. lead a discussion concerning the differences in exothermic and endothermic reactions.
3. distribute Handout 1: Exothermic or Endothermic? on which students will list whether a given reaction
is endothermic or exothermic.
4. distribute Handout 3: Heating Things Up which the students will use for recording their data.
5. supervise and facilitate students during the ice cream experiment.
Student Activities: The student will
1. participate in a discussion concerning the differences in exothermic and endothermic reactions.
2. discern whether a given reaction is exothermic or endothermic and label each given reaction using
Handout 1: Exothermic or Endothermic?
3. complete the assigned experiment as detailed on Handout 3: Heating Things Up. Students will place
the zippered plastic bag containing the ice cream ingredients into another zippered plastic bag that
contains a measured amount of ice and salt. Students will use a thermometer to measure the
temperature of the ice/salt mixture and record that temperature on Handout 3: Heating Things Up.
Students will then shake the bags for 2 minutes and will again measure the temperature of the ice/salt
mixture. Students will continue to shake and measure the temperature in two- minute intervals until the
ice cream begins to solidify (approximately 6 to 8 minutes). A final temperature measure will be taken
and recorded.
4. be allowed to eat the results of the experiment.
5. record the temperatures found during the experiment in a Microsoft Excel spreadsheet.
6. make a graph showing the temperature data recorded during the experiment using the chart wizard
option.
7. Students will use the graphs to show whether the reaction of the salt/ice mixture was an exothermic or
endothermic reaction.
Accommodations:


Those teachers who do not have computers in their classrooms should reserve the media center or a
laptop cart.
Substitute ice cream ingredients if necessary for students who are allergic to milk.
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Page 3
Extension Activities:
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
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Students could study the thermodynamics of refrigeration.
Students could enter their temperature data into an Excel spreadsheet and write a formula converting
Fahrenheit to Celsius.
Students could study cryonics (freezing bodies in order to resuscitate them at a later date when a cure
is available for their diseases).
Integration:
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
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Technology
Language Arts
Home Economics
Assessments:
1. Teacher Observation
2. Completed Graph
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Handout 1
Exothermic or Endothermic?
Decide whether each of the following reactions is exothermic or
endothermic. Use of the Web, your textbook or other resource
books is permitted in order to research your answers. List the
items under the correct column heading below.
1. Melting ice cubes
6. Evaporation of water
2. Rusting iron
7. Freezing ice cubes
3. Baking bread
8. A candle flame
4. Condensation of rain
9. Burning sugar
5. Production of sugar in photosynthesis
Exothermic Process
10. Cooking an egg
Endothermic Process
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
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__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
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Attachment K
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Handout 2
Ice Cream Recipe and Directions
Plastic Bag Ice Cream Recipe*
½ cup milk
½ teaspoon vanilla
1 tablespoon sugar
4 cups crushed ice
4 tablespoons salt
2 quart-size Zip-loc bags
1 gallon-size Zip-loc bag
 Mix the milk, vanilla, and sugar together inside one of the quart size bags.
 Seal tightly, allowing as little air to remain in bag as possible. Too much air left inside may
force the bag open during shaking.
 Place this bag inside the other quart size bag, again leaving as little air inside as possible and
sealing well. By double bagging the ingredients, the risk of salt and ice leaking into ice cream is
minimized.
 Put the two bags inside the gallon size bag and fill the bag with ice, then sprinkle salt on top.
Again let all the air escape and seal the bag.
 Wrap the bag in the towel or put your gloves on, and shake and massage the bag, making
sure the ice surrounds the cream mixture. The mixture should freeze into ice cream within
five to eight minutes.
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Handout 3
Heating Things Up With Ice Cream
Data Record Sheet
Hypothesis: _____________________________________________________________
_____________________________________________________________________________
Procedure: ___________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
Time:
Temperature:
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
Conclusion: ___________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Enter the temperatures above on your spreadsheet and make a graph using the graphing tool on the
spreadsheet software.
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Page 1
Exothermic or endothermic?
This is a useful class practical to introduce e nergy changes in chemical reactions. The students measure the
temperature changes in four reactions, and classify the reactions as exothermic or endothermic. The
experiments can also be used to revise different types of chemical reaction and, with some classes, chemical
formulae and equations.
Lesson organization
There are five solutions and three solids involved. Careful consideration will need to be given as to the most
appropriate way to dispense these to the class. Special care should be taken with the magnesium ribbon and
magnesium powder and, with some classes, teachers may prefer to dispense these materials directly.
The length of time required for carrying out the actual reactions is around 30 minutes, but this will depend on
the nature of the class and how the practical is organized.
Apparatus and chemicals
Eye protection
Each group of students will need:
Polystyrene cup (expanded polystyrene)
Beaker (250 cm3 ) in which to stand the polystyrene cup for support (see note 1)
Thermometer (–10°C to 110°C)
Measuring cylinder (10 cm3 ), 2
Spatula
Absorbent paper
Access to the following solutions:
(all at approx 0.4 mol dm –3 concentration); (see note 2)
Copper(II) sulfate (Low hazard)
Hydrochloric acid (Low hazard)
Sodium hydrogencarbonate (Low hazard)
Sodium hydroxide (Irritant)
Sulfuric acid (Low hazard)
Access to the following solids (see note 3):
Magnesium ribbon (Highly flammable), cut into 3 cm lengths.
Magnesium powder (Highly flammable).
Citric acid (Irritant).
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Page 2
Technical notes
Copper(II) sulfate (Low hazard) Refer to CLEAPSS Hazcard 27C and CLEAPSS Recipe Card 19
Hydrochloric acid (Low hazard) Refer to CLEAPSS Hazcard 47A and CLEAPSS Recipe Card 31
Sodium hydrogencarbonate (Low hazard) Refer to CLEAPSS Hazcard 95C and CLEAPSS Recipe Card 64
Sodium hydroxide (Irritant) Refer to CLEAPSS Hazcard 91 and CLEAPSS Recipe Card 65
Sulfuric acid (Low hazard) Refer to CLEAPSS Hazcard 98A and CLEAPSS Recipe Card 69
Magnesium ribbon (Highly flammable) Refer to CLEAPSS Hazcard 59A
Magnesium powder (Highly flammable) Refer to CLEAPSS Hazcard 59A
Citric acid (Irritant) Refer to CLEAPSS Hazcard 36C
1 Typical expanded polystyrene cups fit snugly into 250 cm3 squat form beakers. This provides a more stable
reaction vessel and also prevents spillage if the polystyrene cup splits.
2 At the suggested concentrations, the solutions (except for sodium hydroxide) represent minimal hazards,
although it is probably advisable to label them as Harmful. If the concentrations are increased then the
solutions must be labelled with the correct hazard warning. The solutions could be provided in small (100
cm3 ) labelled conical flasks or beakers.
3 Small amounts of the solids can be provided in plastic weighing boats or similar. The teacher may prefer to
keep the magnesium ribbon and powder under their immediate control and to dispense on an individual basis.
Procedure
SAFETY: Wear eye protection throughout.
Reaction of sodium hydroxide solution and dilute hydrochloric acid
a Stand the polystyrene cup in the beaker.
b Use the measuring cylinder to measure out 10 cm3 of sodium hydroxide solution and pour it into the
polystyrene cup.
c Measure the initial temperature of the sodium hydroxide solution and record it in a suitable table.
d Measure out 10 cm3 of hydrochloric acid and carefully add this to the sodium hydroxide solution in the
polystyrene cup. Stir with the thermometer and record the maximum or minimum temperature reached.
e Work out the temperature change and decide if the reaction is exothermic or endothermic.
f Discard the mixture (in the sink with plenty of water). Rinse out and dry the polystyrene cup.
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Page 3
Reaction of sodium hydrogencarbonate solution and citric acid
a Repeat steps a – c of the previous experiment, using sodium hydrogencarbonate solution in place of sodium
hydroxide solution.
b Add 4 small (not heaped) spatula measures of citric acid. Stir with the thermometer and record the
maximum or minimum temperature reached.
c Work out the temperature change and decide if the reaction is exothermic or endothermic.
d Discard the mixture (in the sink with plenty of water). Rinse out and dry the polystyrene cup.
Reaction of copper(II) sulfate solution and magnesium powder
a Repeat steps a – c of the first experiment, using copper(II) sulfate solution in place of sodium hydroxide
solution.
b Add 1 small (not heaped) spatula measure of magnesium powder. Stir with the thermometer and record the
maximum or minimum temperature reached.
c Work out the temperature change and decide if the reaction is exothermic or endothermic.
d Discard the mixture (in the sink with plenty of water). Rinse out and dry the polystyrene cup.
Reaction of sulfuric acid and magnesium ribbon
a Repeat steps a – c of the first experiment, using sulfuric acid in place of sodium hydroxide solution.
b Add one 3 cm piece of magnesium ribbon. Stir with the thermometer and record the maximum or minimum
temperature reached.
c Work out the temperature change and decide if the reaction is exothermic or endothermic.
d Once all the magnesium ribbon has reacted, discard the mixture (in the sink with plenty of water). Rinse out
and dry the polystyrene cup.
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Page 4
Teaching notes
The reactions and types of reaction involved are:
Sodium hydroxide + hydrochloric acid → sodium chloride + water (Neutralisation)
NaOH(aq) + HCl(aq) → NaCl(aq) + H2 O(l)
Copper(II) sulfate + magnesium → magnesium sulfate + copper (Displacement, Redox)
CuSO 4 (aq) + Mg(s) → MgSO 4 (aq) + Cu(s)
Sulfuric acid + magnesium → magnesium sulfate + hydrogen (Displacement, Redox)
H2 SO4 (aq) + Mg(s) → MgSO 4 (aq) + H2 (g)
At this level the neutralisation reaction between sodium hydrogen carbonate and citric acid may be a bit
complicated – it may be better to just use the word equation. More able students could use H+(aq) to represent
the acid.
Sodium hydrogencarbonate + citric acid → sodium citrate + water + carbon dioxide
NaHCO 3 (aq) + H+(aq) → Na+(aq) + H2 O(l) + CO 2 (g)
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Attachment M
CLE: 1.1.B.a
Page 1
Using Environmental Models to Determine the Effect of Acid Rain
on an Ecosystem
LEARNING OUTCOME
After completing a reading on acid precipitation and pH, and conducting small -scale
investigations of the effect of acid on aquatic and terrestrial ecosystems, students are able to
predict the environmental effects of acid precipitation.
LESSON OVERVIEW
In this lesson, students select one of two questions associated with acid precipitation and design
an experiment that addresses a question. Students complete a short reading that provides
background information on acid precipitation and pH. They also conduct a literature search to
find out more about acid precipitation.
In addition to designing a controlled experiment, students become involved in the process of modeling. They
use small containers to represent ecosystems, and manipulate a single variable in order to determine its
impact. By using multiple, small setups, students predict what is likely to happen on a larger scale in the
environment.
MATERIALS
Materials required per team of two students will vary, depending on how many replications and trials the team
elects to do. What students decide to bring in from home will also result in variation in materials used. The
two questions, and the necessary items to be used in investigating them, are:
A. How does acid precipitation affect aquatic ecosystems?
• 200 mL of dilute sulfuric acid or white vinegar
• 200 mL of distilled water
• 1 L of pond water containing aquatic organisms. Algae and plants such as duckweed should be
obvious and plentiful in the pond water.
• 2 graduated cylinders (1 100- mL and 1 10- mL)
• 2 or more pipettes for applying the acid and distilled water
• 4 or 5 plastic cups (6-, 8-, or 10-oz. are acceptable)
• marking pen
H paper or pH meter
• slides and cover slips
• compound microscope or stereoscope
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Page 2
B. How does acid precipitation affect terrestrial ecosystems?
• 200 mL of dilute sulfuric acid or white vinegar
• 200 mL of distilled water
• 1 100-mL graduated cylinder
• 1 10-mL graduated cylinder
• 2 or more pipettes for applying the acid and distilled water
• 4 or 5 plastic cups (6-, 8-, or 10-oz. are acceptable)
• 1 metric ruler
• marking pen
• pH paper or pH meter
• slides and cover slips
• compound microscope
• soil*
• seeds or small plants
*Have students bring in ―real‖ soil for use in their experiments. The results will be more authentic because
the soil will contain organisms, natural buffers, etc. In a pinch (as a backup for those who do not comply),
potting soil will work—but soil from a local habitat is preferable.
SAFETY
• Caution students to use ―reasonable‖ quantities of sulfuric acid or vinegar since this is a small-scale
experiment.
• Insist that students wear goggles and gloves when handling the acid, pond water, and soil. They may
protest, but wearing goggles and gloves is good laboratory practice.
• Have students obtain permission from you prior to bringing ancillary items from home, and again, prior to
their use in school.
• Caution students to wash the tabletops and their hands after handling laboratory materials.
TEACHING THE LESSON
• You might choose to set up these chalk activities as a demonstration. Use containers of clear liquid
(white vinegar or dilute sulfuric acid) labeled ―Liquid X‖ and ―Liquid Y.‖ Add these liquids to the
containers of chalk. Have students make observations and record them in their notebooks. At this point
there is no need to share observations. Indicate to students that their observations should be exact;
should changes occur by the next day’s class period, they are more likely to be noticeable.
Drain the liquids off into separate beakers having the appropriate labels. Elicit observations for both the
chalk and the liquids. Have students refer to the notes made the day before and describe any differences.
Call on students willing to share one of the differences they have observed.
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Students should come to the conclusion that the two liquids are different. Use pH paper to establish that one
is more acidic than the other. This is a good way to introduce or review pH. Then ask students what they
know about acid precipitation and its impact on the environment as a natural way to lead into the reading
and design components of the lesson.
• Point out to students that scientists can control variables in artificial ecosystems, and this allows them to
study food webs, and energy flow through an ecosystem, more easily than in a natural ecosystem. Acid
precipitation impacts an ecosystem by disrupting food webs and therefore energy flow. But this is not
the typical perception. Students are likely to think that acid precipitation is a problem because it kills
organisms. This is true marginally but is just a small part of the ―big picture.‖ Biosphere II is a large
artificial environment that you might want students to investigate. Although some scientists view the
project as a failure scientifically, others feel that the research community has learned much from the
endeavor. Students will establish many smaller scale artificial ecosystems. By controlling variables,
students can obtain information about interactions within these ecosystems. Students should be aware
that their results will serve only to predict what may happen in a natural ecosystem.
• To prepare dilute sulfuric acid, measure 5.5 mL of concentrated H2 SO4 and pour it slowly, while stirring,
into 1 L of distilled water. Another option is to have students use white vinegar, which has a pH of 4.
Either liquid should provide observable differences in the student setups.
• The ability of the soil to resist some pH change is called ―buffering capacity.‖ Without any buffering
capacity, soil pH changes rapidly. Typically, the buffers maintain the pH of the soil through numerous
assaults of acid. This presence or absence of buffers may be a factor in the investigations some students
design and carry out for this lesson. Since the pH of the 0.1 molar sulfuric acid and white vinegar is not
extremely low, the buffering capacity of the soil may maintain the pH students measured at the
beginning of the experiment. Garden soil is a better choice than potting soil. If you must use potting soil,
check the potting soil label to make sure that lime or other buffers have been added, or purchase one that
is suitable for acid- loving plants such as rhododendrons.
• Students may need help in determining how to measure soil pH. Have them place about 5 or 10 grams of
soil in a glass jar/beaker and mix it with 10 or 20 mL of distilled water. They can then use pH paper to
determine the pH of the soil. If using a pH probe, mix 30 grams of soil with 60 mL of distilled water and
let the mixture sit overnight. Pour the water from the top of the mixture into a clean, dry beaker. Follow
the instructions for the pH probe system you use.
• Plants students might use include coleus, begonia, or grass. (They can plant the seed directly in their
cups, or to shorten the time needed, you could plant several large, flat containers with grass seed about
two days before you plan to do the activity. That way you can ―cut‖ sections from your planting and
place these in the student containers on top of an appropriate amount of soil.) There are many other
suitable plants that are easy to obtain and/or grow. Rapid radishes and brassica are two plants with short
life cycles that are easy to grow. The systems described in many science supply catalogs are not
necessary for the successful use of these plants in the classroom. The light and fertilizer requirements
should be heeded.
At some point in the lesson, refer students to the ―Avoided Emissions‖ screen of the photovoltaic system
display. Ask students how the information provided relates to what they are doing. Help them see that
alternative energy forms can lessen the amount of sulfur dioxide and nitrogen oxides released into the
atmosphere and thus lessen the amount of acid deposition.
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ACCEPTABLE RESPONSES FOR DEVELOP YOUR UNDERSTANDING SECTION
Activity Analysis
•
Any number of hypotheses are possible. Be sure that students write hypotheses in an acceptable format,
and do not simply write a question or problem statement. An acceptable hypothesis does not have to be
true but it does need to be testable. Sample hypotheses are listed below:
Acid rain impacts plant survival.
The level of acid precipitation affects the growth of plants.
Acid precipitation affects the diversity of organisms that can live in an area.
•
•
•
•
Any number of procedures are possible. Be sure that students include replications (repeated trials). One
cup having a different pH than another, or one plant in each setup, will not provide statistically valid
results.
Sample controls are a cup or cups of pond water or soil with tap water added. The tap water should be
added to the terrestrial control cup(s) in the same amounts and on the same schedule as the acid is added to
the experimental cups. Rainwater or melted snow would be a better control than tap water. However, tap
water is readily available and should be somewhat reflective of the precipitatio n received in the area. This
is truer in rural areas than in urban. Additional water should also be added to the aquatic control on the
same schedule as acid is added to the experimental containers. Caution: Be sure to allow the water to sit
overnight before using if it has been treated with chlorine. The experimental cups would have acid added
on the same schedule. Students may want to apply more drops to indicate a lower pH (more acid rain), or
they may wish to dilute the acid by adding distilled water. For example, they may wish to mix x mL of
acid with y mL of distilled water for one setup, x mL of acid with z mL of distilled water for a second, and
so forth. Of course, they can add ―straight‖ acid to some of the setups.
The independent variable is the amount of acid added to the setups.
The dependent variable might be the amount of plant growth, or the diversity of the population of
organisms present.
• The final report should include the approved Experimental Design Matrix; student observations to be
evident through drawings, measurements, photos, and so forth, to be presented through such devices as
dated charts and graphs; and a conclusion based on the results of the experiment. Students should be sure
to indicate whether the hypothesis they were testing was supported or not supported.
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Extended Activities
• Have students observe the effect of acid rain on marble and limestone. These are two commonly used
building materials.
(1) Label two beakers or plastic cups as follows: ―chalk in vinegar‖ and ―chalk in water.‖
(2) Have students place a piece of chalk in each beaker or plastic cup.
(3) Next, students should be directed to pour enough white vinegar into the container labeled ―chalk in
vinegar‖ to cover the chalk.
(4) Students should then add enough water to the ―chalk in water‖ container to cover the chalk.
(5) Let the dishes stand overnight.
(6) After a day or two, have students remove the chalk from the two containers and observe any
differences. They should see that the chalk in the vinegar is more worn away. These observations are
intended to reveal through analogy the effect of acid rain on structural marble and limestone. Chalk
is composed of calcium carbonate. In addition to being an ingredient of chalk, calcium carbonate
occurs in rocks such as marble and limestone. It is also found in some animal bones, and in shells
and teeth. For more information go to
http://mineral.galleries.com/minerals/carbonat/calcite/calcite.htm
• Students might construct ecocolumns using two- liter clear plastic soda bottles. Directions for constructing
the ecocolumns can be found in ―Bottle Biology,‖ published by Kendall/Hunt Publishing Company, 2460
Kerper Boulevard, P.O. Box 539, Dubuque, Iowa 52004-0539. Students could construct larger model
ecosystems and manipulate selected variables over a longer period of time.
• Invite an expert speaker from a government agency such as the Missouri Department of Environmental
Conservation, or from a local college, to talk with the students about acid precipitation in Missouri and
other states
•
Relate this science activity to art and literature. Students could read a book such as The Giving Tree by
Shel Silverstein or A Tree Grows in Brooklyn by Betty Smith. They could then discuss the significance of
trees in the book. They would need to bring together real-world science problems and literary symbolism.
Another book for use with this lesson is The Sky Tree, written by Candace Christiansen. It brings science
and art together, using the theme of changing seasons. Oil paintings show a single tree and its
surroundings as the seasons change from winter to autumn. Scenes of clouds, birds, and stars challenge the
reader to imagine the tree interacting with the sky and its inhabitants. The text points out incremental
changes in atmosphere and their effects. Each image is paired with a question or two such as ―Why does
this painting make you feel sad? Is the tree dying?‖ and ―How does this painting capture the stillness of a
snowy day?‖
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BACKGROUND INFORMATION
As the water from rain or snowmelt moves down through the soil, some or all of its acidity may be neutralized
by naturally occurring buffers. Soils in regions of the Northeast, such as New York’s Adirondack Mountains,
have little buffering capacity. In the Adirondack Mountains, the natural buffers are not there in large quantities
due to the composition of the soil. In other areas, over time, soils lose their ability to buffer acid precipitation.
The application of lime to both terrestrial and aquatic systems in New York State represents one attempt to
help boost an ecosystem’s buffering capacity. In terms of both time and money, this is a costly way to
remediate the impact of acid precipitation, especially since such applications must be repeated periodically.
Acid rain does not usually kill trees directly but weakens them by damaging their leaves, thus limiting
available nutrients, or by poisoning them with toxic substances that are slowly released from the soil. Acidic
water reacts with and dissolves nutrients in the soil and then washes them away before plants can use them.
Acid rain also causes the release of toxic substances such as aluminum into the soil. These substances are very
harmful to plants, even if contact is limited.
It is not only below the ground where acid precipitation causes problems, but also above. Forests in mountain
areas receive acid from the clouds and fog that often surround them. The clouds and fog are often more acidic
than rainfall. When leaves are bathed in acid fog, their protective waxy coating is gradually eaten away.
Leaves that have lost this coating are damaged upon further exposure. Brown spots are one sign that this is
happening. The damaged leaves cannot carry out sufficient photosynthesis to produce an adequate food supply
for the plant. The weakened plants are more likely to be attacked by insects and a variety of plant diseases.
They are also more likely to be injured by cold weather.
The effects of acid rain are clearly seen in aquatic environments such as streams and lakes. Such bodies of
water have a natural pH somewhere between 6 and 8. Some lakes, however, are naturally acidic. They
typically become acidic when the water in the lake and surrounding soil cannot buffer the acid precipitation
enough to neutralize it. In different parts of the northeastern United States where the soil buffering ability is
poor, some lakes now have a pH of less than 5. Little Echo Pond in Frank lin, New York, is one of the most
acidic lakes known: it has a pH of 4.2.
Generally, the young of most species are more sensitive than the adults. Adult frogs may tolerate relatively
high levels of acidity, but may die out if insects such as the mayfly are a large part of their diet. The mayfly
cannot tolerate a pH less than 5.5. When the mayfly population is reduced, then the frog population is reduced,
and in fact may disappear if mayflies represent a large enough part of the frogs’ food supply. As lakes and
streams become more acidic, the numbers and types of fish and other aquatic organisms decrease. For some
types of plants and animals, a lower pH is not a problem; these types are able to tolerate acidic waters. Other
organisms, however, are acid-sensitive and will have to move or die out as the pH declines. Some lakes are
so acidic, they lack fish altogether. At pH 5, most fish eggs fail to hatch. At lower pH levels, even some adult
fish die. Toxic substances such as aluminum that wash into the water from the soil also kill fish and other
aquatic organisms, typically by affecting the intake of oxygen in the gill area.
The air pollution that causes acid rain is damaging to human health. Sulfur dioxide and nitrogen oxides, the
major sources of acid rain, irritate or even damage our lungs. The primary pollutant associated with acid rain
is sulfur dioxide. Emissions of sulfur dioxide form small sulfate particles, or aerosols, in the atmosphere.
Nitrogen oxide emissions are also associated with the formation of acid precipitation.
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In 1980, Congress established the National Acid Precipitation Assessment Program (NAPAP) to conduct a
comprehensive ten- year research, monitoring, and assessment program o n the causes, effects, and controls of
acid rain. In 1996, NAPAP conducted an integrated assessment of cost benefits and effectiveness of acid rain
controls specified in the 1990 Clean Air Act Amendments as implemented by the U.S. Environmental
Protection Agency. Some of the findings are:
• There have been reductions in SO 2 emissions since 1980.
• The acidity of, and sulfate concentrations in, precipitation have decreased in the midwestern, middle
Atlantic, and northeastern regions of the United States.
• Since 1980, lakes and streams throughout many areas of the United States have experienced decreases in
sulfate concentrations. Additional reductions in sulfur and nitrogen deposition would be required for full
recovery of sensitive Adirondack lakes.
• Sulfur and nitrogen deposition has caused adverse impacts on certain highly sensitive forest ecosystems
in the United States, especially high-elevation spruce- fir forests in the eastern United States. If
deposition levels are not reduced in areas where they are currently high, adverse effects may develop in
more forests due to chronic, multiple-decade exposure.
• Decreased emissions are expected to reduce fine-particulate sulfate and nitrate concentrations in air,
possibly leading to reductions in adverse health effects.
• Quantifiable economic benefits could be relatively large in the areas of human health and visibility and
exceed the costs of reducing emissions.
In 1990, Congress passed the landmark Acidic Deposition Control Program as Title IV of the 1990 Clean Air
Act Amendments (Public Law 101-549). The Acid Deposition Control Program mandates by 2010 a 40%
annual reduction in the emissions of sulfur dioxide (SO 2 ) from a 1980 base, and imposes a national cap of
about 15 million tons. In addition, annual emissions of nitrogen oxides (NOx) from stationary sources were to
be cut by about 10% by the year 2000. However, there is no national cap on the emissions of nitrogen oxides.
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Name ___________________________________
Date ____________________________________
Using Environmental Models to Determine the Effect of Acid Rain on an Ecosystem
Background Information
Acid precipitation, usually called acid rain, consists of sulfuric and nitric acids in t he atmosphere. These acids
reach Earth’s surface in rain, snow, sleet, fog, hail, or dew. Acid precipitatio n is a large problem in Missouri
State and in other eastern regions of North America.
The pH scale (which measures acidity) is used to determine if precipitation is acidic. In this scale, the smallest
numbers are the most acidic and the largest numbers are the least acidic (most ―basic‖ or alkaline). A pH of 7
is neutral. It is neither acidic nor basic.
distilled water
pH Scale
lemon juice “natural rain” baking soda
0
1
2
3
ammonia
4 5
6 7
8 9 10 11 12
increasing neutral increasing
acidity
alkalinity
13 14
The pH scale is a ―power of 10‖ scale. This means that a liquid with a pH of 5 is ten times as acidic as a liquid
having a pH of 6. It is 100 times as acidic as a liquid having a pH of 7. pH is typically measured with litmus
paper, pH paper, or pH meter. There are other indicators (chemicals that change color at a specific pH).
The main ingredients in acid precipitation are sulfur dioxide (SO 2) and nitrogen oxides (NO x). These gases are
produced naturally by volcanic activity and electrical storms. Another source of these gases is the burning of
fossil fuels. Industries such as smelters and electric generating plants emit sulfur dioxide. Cars, trucks, buses,
and power plants emit nitrogen oxides. Sulfur dioxide and nitrogen oxides enter the atmosphere as gases and
then, through a series of chemical reactions, they are changed to acids.
Precipitation has a natural pH of 5.6. It is slightly acidic due to carbon dioxide in the air combining with water
vapor to form a weak acid, carbonic acid. For thousands of years, ecosystems in northeastern North America
have received precipitation with a pH of 5.6. Within the last 100 years, the pH of precipitation in the United
States has become increasingly acidic. Annual rainfall in much of the northeastern U.S. now has an average
pH of 4.2 – 4.6. This is more than ten times as acidic as ―natural‖ rain.
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Acid precipitation has harmful effects on the environment. Scientists continue to investigate the effects of the
increasing acidity of the soil and water. Acid precipitation is responsible for making lakes in the Adirondack
Mountains and other areas of the world too acidic for fish and other living organisms. Acidic precipitation
washes nutrients from the soil, making them unavailable for plants. Toxic metals such as aluminum become
soluble in lake water, causing adult fish to die. These toxic metals may also be absorbed by tree roots,
eventually killing the trees. Acids in the air are responsible for slow, long-term damage to statues, stone
buildings, paint on automobiles, and metals.
Scientists question just how much acidity various ecosystems can handle. Through computer simulation,
environmental models allow scientists to study what could happen to organisms in an ecosystem if there are
changes in the abiotic components. Models help scientists check predictions without disrupting large
ecosystems.
You are to design an experiment to model what the effect of acid precipitation might be on an aquatic
ecosystem or a terrestrial ecosystem.
Question
Select one of the two questions below to investigate. Record the question in the appropriate place on your
Experimental Design Matrix.
A. How does acid precipitation affect an aquatic ecosystem?
Materials and equipment you have available for use include:
• dilute sulfuric acid and/or white vinegar
• distilled water
• pond water containing aquatic organisms
• pipettes
• graduated cylinders
• plastic cups
• marking pen
• pH paper or pH meter
• slides
• cover slips
• compound microscope and stereoscope
• You may request additional materials or obtain permission to bring in other items from home.
B. How does acid precipitation affect terrestrial ecosystems?
Materials you have available for use include:
• dilute sulfuric acid and/or white vinegar
• distilled water
• pond water containing aquatic organisms
• pipettes
• graduated cylinders
• plastic cups
• metric ruler
• soil
• seeds
• small plants
• marking pen
• pH paper or pH meter
• slides
• cover slips
• compound microscope
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Hypothesis
• Begin by doing research on one of the questions.
• Prepare a one-page report on the problem as a preliminary step to developing your investigation. Include a
bibliography of the books and/or Internet sites you used in collecting information.
• Create a hypothesis for the question you are investigating. The hypothesis is formulated on the basis of
observations and other knowledge gained by experiences and/or research. The hypothesis is a proposed
explanation about the relationship between the variables that can be tested. An example of a hypothesis for
a different investigation is ―Fertilizer will influence the growth of tomato plants.‖
• Record your hypothesis in the appropriate place on the Experimental Design Matrix.
Title
• You may want to decide on your title last. The title should tell the reader what you are trying to find out.
Use the following as a guide: ―The Effect of (independent variable) on (dependent variable) in
(organism/ecosystem studied).‖
• A statement of what is being investigated should include the independent variable, the dependent variable,
and the organism (or ecosystem) being studied. An example is ―The Effect of Fertilizer on Tomato Plant
Height.‖
• Once you have written your title, record it in the appropriate place on the Experimental Design Matrix.
Experime ntal Design
• Discuss with your partner the design of an experiment that will answer the question you have chosen to
investigate. Identify your dependent and independent variables.
• Record the dependent and independent variables and include a description of how this is a controlled
experiment in the appropriate places on the Experimental Design Matrix.
• Be sure to include safety precautions in the appropriate place. Record these in the Experimental Design
Matrix.
• Before writing out the procedure for your experiment, show your completed Experimental Design Matrix
to your teacher. Once it has been reviewed and approved, finish designing your experiment.
Procedure
• Write out step-by-step procedures. Be sure to include the amounts of materials, number of trials, and
measurements and observations you will make. Decide how you will keep track of data you collect during
the experiment. Will you make drawings, take pictures, use a data table or graph?
• Collect your materials, review your procedure, and conduct your experiment!
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Analysis
Analyze the results of your experiment by doing the following:
(1) Organize your data in table(s), graph(s), and/or a series of illustrations/photos.
(2) Draw a conclusion—decide and describe whether your hypothesis is supported or not supported by the
data collected.
(3) Prepare and submit a final report of your research. It should include: your approved Experimental
Design Matrix; listing of the procedures followed; observations, drawings, photos, and data collected;
graphs and charts; and conclusion.
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Name____________________________________________
Experi mental Design Matrix
Question asked
Hypothesis
Title of the experiment
Independent (mani pul ated) variable
Dependent (res ponding) variable
Descripti on of variables hel d constant
Descripti on of how this is a controlled experi men t
Materials and equi pment needed to conduct the experiment
Safety precautions
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Experi mental Design Matrix
Question Asked
The question is what you are curious about. It is what you would like to know. Examp les of possible questions are ―Does fertilizer
affect the growth of to mato plants?‖ and ―Does adding fertilizer make tomato plants grow better?‖
Hypothesis
The hypothesis is formulated on the basis of observations and oth er knowledge gained by experiences and/or research.
The hypothesis is a proposed explanation about the relationship between the variables that can be tested.
An examp le is ―Fert ilizer will influence the growth of to mato plants.‖
Title of the Experi ment
What are you trying to find out? An example is ―The Effect of ( independent variable) on (dependent variable) in (organism or
ecosystem studied).‖
A statement of what is being investigated should include the independent variable, the dependent variable, and the organism being
studied. An examp le is ―The Effect of Fertilizer on Tomato Plant Height.‖
Independent Variable
What are you testing in your experiment? What are your units of measurement?
The variable that is changed on purpose and the units that are used for measurement of this variab le are established by the
experimenter. An example is ―Fert ilizer concentration could be expressed in %.‖
If it is appropriate, you should also record the levels of the independent variable. Examine the chart below.
Levels of Independent
Variable
For amounts of independent variable, you could
list, fo r examp le, ―0, 5, 10, 15, and 20 drops of
fertilizer.‖
Number of Repeated
Trials
This would be the number of times tested or the
number of objects/organisms tested at each level
of the independent variable. For example, you
might test four tomato plants at each
concentration of fert ilizer.
--------->
in
increasing
order
--------->
Dependent Variable
What results will you measure? What are your units of measurement? An examp le is ―tomato plant height (cm).‖
Descripti on of Variables Hel d Constant
This must be the same in every setup so that you will know that any differences you observe are due to the variable you are t esting.
In the fertilizer experiment, you will use the same species of plants. They should be the same size, gro wn in identical containers of
soil that receive the same amount of water and light. They should all be kept at the same temperature.
Control
What is the control in your experiment? How would you convince someone that your experiment is a controlled experiment?
The control in an experiment is usually the group that is used as a standard for comparison. It is typically the group that r eceives no treatment. You could describe the
control group as ―the group of tomato plants that were treated with 0% fertilizer.‖ Or you could state that your experiment was controlled because ―only the fertilizer
concentration was changed in each setup—all other factors were kept the same.‖
Safety Precauti ons
It is impo rtant that safety precautions be described. Since someone else may want to repeat your experiment, you should descr ibe
how to do it safely.
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Atmosphere WebQuest Links
Atmosphere WebQuest Worksheet (see attached)
WEBSITE #1:
www.zoomschool.com/subjects/astronomy/planets/earth/Atmosphere.shtml
WEBSITE #2:
http://www.epa.gov/ozone/science/
WEBSITE #3:
http://www.geo.mtu.edu/weather/aurora/
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FIRST, GO TO WEBSITE #1.
What is Earth’s atmosphere?
________________________________________________________________________
________________________________________________________________________
What is it composed of?
_______________________
80
70
60
50
40
30
20
10
0
_______________________
_______________________
_______________________
How was the atmosphere formed?
A
B
C
D
gases
________________________________________________________________________
________________________________________________________________________
Three functions of Earth’s atmosphere are:
___________________________________________
___________________________________________
___________________________________________
Can we change the composition of the atmosphere? If so, how?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
What is air pressure at sea level? How much does it change as you reach an altitude of 10,000 feet?
________________________________________________________________________
________________________________________________________________________
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NOW, GO TO WEBSITE #2.
Click on ―Questions and Answers (brief)‖. Page down, and read all 6 sections.
What is the ozone layer and why is it important?
________________________________________________________________________
________________________________________________________________________
How does ozone depletion occur?
________________________________________________________________________
________________________________________________________________________
What is being done about ozone depletion?
________________________________________________________________________
________________________________________________________________________
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