Lab 12 - CHEMICAL BONDING LAB
A COMPARISON OF FOUR TYPES OF BONDING
Chemical and physical properties are determined by the type of bonding in a substance and by the polarity of the substance. In this series of
activities, you will observe a variety of phenomena which occur because for the type of compound.
Around the room are placed different activities, each designed to illustrate properties and phenomena associated with molecular type, bonding
and polarity. You may begin anywhere and move from station to station. Carry out the activity as described in the directions, write down any
observations or data and answer the questions written for each activity.
You will be working with five solids: sodium chloride (NaCl), sucrose (C12H22O11), metallic copper (Cu) naphthalene (C10H8) and cetyl
palmitate (C32H64O2). Sodium chloride is an ionic solid, sucrose is a polar covalent solid, copper is a metallic solid and cetyl palmitate and
naphthalene are nonpolar covalent solids.
Prelab:
Design a data table that will contain the results of each of the following seven activities. Use an entire sheet of paper for this.
1. A Comparison of Melting Points
IN THIS ACTIVITY YOU ARE TO COMPARE THE
MELTING POINTS OF FOUR SOLIDS. BY HEATING
THEM SIMULTANEOUSLY, YOU CAN DETERMINE
WHICH MELTS FIRST, WHICH NEXT AND WHICH LAST.
At these stations, you will find a ring clamp attached to a ring
stand and several tin can lids. Place 3-4 grains of each solid on
the edge of the lid so that the piles are evenly spaced around the
outside edge of the lid.
Make sure you know where each solid is placed!
Light the candle and put it directly under the center of the lid –
make sure the lid is no further than an inch from the flame.
Observe which of the solids melts first, which next, etc.
After 2 minutes, blow the candle out even if some solids have
not yet melted. Record your observations.
Disposal: After the lid has cooled, dump the solids into the
trash and clean the lid.
In a solid, the atoms or molecules are arranged in a highly ordered
structure. The atoms or molecules are held in a rigid structure by
intermolecular forces. To melt a solid, these intermolecular forces
must be overcome, thereby allowing the atoms or molecules to
move freely in the liquid state.
Based on your observations, what general statements can you make
about the relative melting point of an ionic compound, a polar
compound, a nonpolar compound and a metallic solid when
compared to each other? Your statements should include an
understanding intermolecular attractions.
2. Solubility in Water
IN THIS ACTIVITY YOU ARE TO COMPARE HOW
WELL EACH OF THE SOLIDS DISSOLVES IN WATER.
WATER IS A POLAR SOLVENT AND THIS PROPERTY
OF WATER MAKES IT ABLE TO DISSOLVE MANY
IONIC AND POLAR MOLECULES. WATER WILL NOT
DISSOLVE A NONPOLAR MOLECULE.
Draw a diagram of a water molecule. Using the diagram, indicate
the polar nature of water.
Draw the structures of sucrose and cetyl palmitate.
YOUR LIFE EXPERIENCES ALREADY TELL YOU
ABOUT THIS. AN OIL AND VINEGAR SALAD
DRESSING HAS TWO LAYERS. THE SALAD OIL IS A
NONPOLAR SUBSTANCE AND THE VINEGAR IS A
WATER SOLUTION OF ACETIC ACID. THE TWO
TOGETHER IN A SALAD DRESSING FORM TWO
DISTINCT LAYERS BECAUSE THE WATER LAYER
WILL NOT DISSOLVE THE SALAD OIL.
IF THE SUBSTANCE HAS DISSOLVED, YOU WILL NOT
SEE IT ANY MORE. IF YOU CAN STILL SEE THE
CRYSTALS, THEN THEY HAVE NOT DISSOLVED.
INDICATE WATER SOLUBILITY WITH THE WORD
“SOLUBLE”. IF THE SUBSTANCE IS NOT SOLUBLE IN
WATER, INDICATE THAT WITH THE WORD
“INSOLUBLE”.
There are four labeled test tubes at this activity station. Each
one contains 0.5g of solid and 5ml of water. Observe which, if
any has dissolved. Record your observations on your report.
DISPOSAL: Replace the test tubes in the rack unopened.
What are the intermolecular forces between
a) sucrose molecules?
b) cetyl palmitate molecules
c) water molecules?
How are the IMF between sucrose molecules similar to the ionic
bonds in sodium chloride?
Why did these compounds behave the way they did in water?
Explain in terms of intermolecular attractions.
3. Conductivity of a Water Solution
IF A SUBSTANCE CONDUCTS
ELECTRICITY WHEN IT IS DISSOLVED IN
WATER, IT IS CALLED AN
ELECTROLYTE. WHEN THE ELECTRICAL
CIRCUIT IN THE SOLUTION IS
COMPLETED, THE LIGHT BULB OR LED
GLOWS BRIGHTLY OR FLASHES.
USE THE KEY ON THE BACK OF THE
CONDUCTIVITY TESTER TO KNOW
WHETHER A SOLUTION IS A STRONG OR
WEAK CONDUCTOR.
There are five small beakers; four contain water
mixed with the indicated solid. The fifth
container contains pure deionized water (not tap
water which has many minerals dissolved in it).
Place the tips of the electrodes in the liquid to
test each of the mixtures and the deionized
water. RINSE THE ELECTRODES WITH
DISTILLED WATER BEFORE TESTING
EACH ONE AND AFTER TESTING THE
LAST.
DO NOT LET ANY WATER GET INTO THE
PLASTIC PIECE HOLDING THE
ELECTRODES!
DISPOSAL: None.
Electrical current is created when the electrons flow from the negative terminal of
a battery through a conductor to the positive terminal of the battery. In order for a
substance or material to conduct electricity the substance must contain charges
that can move freely.
Which of the four solutions of the solids conducted electricity in significant
ammounts?
Why does this dissolved solid allow electrons to flow?
Why doesn’t electricity flow through the solution when sucrose is dissolved in
water?
4. Solubility in Hexane
IN THIS ACTIVITY YOU ARE TO
COMPARE HOW WELL EACH OF THE
SUBSTANCES DISSOLVES IN
HEXANE, C6H14.
INDICATE HEXANE SOLUBILITY
WITH THE WORD “SOLUBLE.” IF THE
SUBSTANCE IS NOT SOLUBLE,
INDICATE THAT WITH THE WORD
“INSOLUBLE.”
When a substance dissolves in another substance, this happens because there is an
attraction between the molecules or ions of the two substances.
What is a solvent?
Draw the Lewis structure of hexane, C6H14 and explain why it is a nonpolar compound.
What intermolecular forces are present in hexane?
There are four test tubes at this activity
station. Each one contains about 5ml of
Which of the four substances dissolve in hexane?
hexane and about 0.5g of the solid indicated.
CAUTION: DO NOT OPEN ANY OF
THE TEST TUBES! Observe each test tube
and identify whether the substance dissolves
in hexane or not.
Why do water and hexane dissolve different substances? Mention both bond type and
intermolecular forces in your explanation.
DISPOSAL: None. Replace all test tubes in
the rack unopened.
5. Conductivity of a Hexane Solution
WHEN THE ELECTRICAL CIRCUIT IN THE
SOLUTION IS COMPLETED, THE LIGHT BULB OR
LED GLOWS BRIGHTLY OR FLASHES.
USE THE KEY ON THE BACK OF THE
CONDUCTIVITY TESTER TO KNOW WHETHER A
SOLUTION IS A STRONG OR WEAK CONDUCTOR.
There are five small containers at this activity station, four
of which contain hexane and the indicated solid. The fifth
contains pure hexane. (CAUTION: HEXANE IS VERY
FLAMMABLE. TAKE CARE NOT TO USE HEXANE
NEAR AN OPEN FLAME.)
KEEP THE CONTAINERS CAPPED AS MUCH AS
POSSIBLE.
Using the conductivity tester, test each of the mixtures and
the pure hexane. Wipe the electrodes of the tester off with
tissue before testing each one and after testing the last.
DISPOSAL: None. Be sure to wipe the electrodes with
tissue and replace all of the caps.
Electrical current is created when electrons flow from the negative
terminal of a battery through a conductor to the positive terminal of the
battery. In order for a substance or material to “conduct electricity” the
substance must allow for the movement of electrons through it.
Which solutions conducted electricity?
Explain why your observations are correct. In your explanation,
demonstrate that you understand why some solutions conduct electricity
and why others do not.
6. Volatility
IN ORDER TO DETECT THE ODOR OF A
SUBSTANCE, THE SUBSTANCE HAS TO BE A
GAS. IF A SOLID VAPORIZES (TURNS INTO A
GAS) EASILY, IT IS BECAUSE THE FORCES
HOLDING THE MOLECULES TOGETHER ARE
WEAK.
Scientists’ use the word “volatility” to describe how easily a substance turns
into a gas. Substances that evaporate easily are made up of molecules that are
not attracted very strongly to each other.
When molecules have a strong attraction for each other, the substance tends to
be nonvolatile.
IF A SOLID DOES NOT VAPORIZE EASILY, IT
IS BECAUSE THE FORCES HOLDING THE
PARTICLES IN THE CRYSTAL ARE STRONG.
Which of the four solids have a significant odor?
THESE DISTINCTIONS ARE NOT OFTEN
CLEAR-CUT, BUT THEY CAN SERVE TO
DIFFERENTIATE BETWEEN IONIC AND
MOLECULAR SUBSTANCES, ESPECIALLY
WHEN COMBINED WITH OTHER
OBSERVATIONS.
Explain how the presence or lack of an odor relates to the type of
intermolecular forces and bonding in each of the four solids.
Sucrose
Naphthalene
At this activity station are placed four stoppered,
labeled test tubes or jars containing the solids under
investigation. Open each test tube and carefully
smell the contents USING THE APPROVED
METHOD FOR DETECTING ODORS.
If you detect an odor, assume that the substance is
volatile (easily vaporized). Record this with a “yes”
on your report sheet. If there is no odor, assume that
the substance is nonvolatile. Replace the stoppers.
DISPOSAL: None
Copper
Sodium chloride
7. Conductivity of a Solid
ELECTRICAL CONDUCTIVITY IS A
VERY REVEALING PROPERTY. YOU
WILL TEST THE CONDUCTIVITIES OF
EACH OF THE SOLIDS, MAKING
NOTE OF THE BRIGHTNESS OF THE
BULB OR LED.
REPORT “YES” IF THE SOLID
CONDUCTS ELECTRICITY AND “NO”
IF THE SOLID DOES NOT CONDUCT
ELECTRICITY.
At this activity station, there are four
labeled beakers or containers containing
the solids. Place the electrodes under the
surface of each of the solids and note the
bulb or LED.
Electrical current is created when electrons flow from the negative terminal of a battery
through a conductor to the positive terminal of the battery. In order for a substance or
material to “conduct electricity” the substance must allow for the movement of
electrons through it.
Which of the four substances conducted electricity?
Explain how the type of bonding in each substance allows or does not allow for the flow
of electrons.
Sucrose
Cetyl palmitate
Copper
Brush off the electrodes with a piece of
tissue before testing the next solid.
Sodium chloride
DISPOSAL: None.
Compare the results of this activity with the other conductivity activities (#3 and 5).
What is similar about each substance and/or solution that did conduct electricity? What
do they have in common?
Lab report evaluation for Bonding Lab
General hints:
 Divide your lab report into these sections. Real scientists divide their “lab reports” (journal articles) into similar sections. You should too.
 Write as clearly and concisely as possible. A chemistry student from any high school in the area should be able to understand what you are explaining.
 Stay focused on your question and the data. Are you using the data to answer the question?
Tell the reader what they are going to see in the report (the CLAIM), show them the experimental results (DATA) and then tell the reader what they have seen
(EVIDENCE). This seems repetitive and awkward but it is how clarity is constructed.
Needs Work
Safety
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Question
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Activities
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Observations
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Claim
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Evidence
Reading
Reflection
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Writing
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Making
Progress
Almost
There
Very Good
List all chemicals used and the specific hazards identification
information for each. This information can be obtained from any
online MSDS. (www.flinnsci.com is my favorite site for MSDS)
Testable question answerable by using the lab data, not your notes.
Question should involve two or more of the activities and be more
complex than just a yes/no question.
Which part(s) of the lab pertain to your question? You must use at
least two of the activities.
Data was recorded accurately and clearly in table form.
5 pts
Claim answers the question correctly.
Claim is derived from the observations.
Claim is one sentence long.
Comes from observation.
Logically supports the claim.
Is your claim supported by the scientific literature?
Please use a text that I have access to, include the book title and page
number or URL so I can reference it. Tell what the text says and how
it supports or disproves your claim.
How did your lab go? How confident are you in your results? If you
had to do it over, what would you do to improve your work?
Correct spelling and complete sentences.
Ideas are presented so that the reader can easily understand them.
4 pts
5 pts
1 pts
1 pts
6 pts
2 pts
1 pts
5 pts
Total: 30 pts