Monday, September 10th
Today:
Chapter 2
Frequency: CD
Chapter 2 - Energy and Matter
Energy
• is the ability to do
work.
• can be classified as
either potential or
kinetic.
• comes from the food
we eat and enables
us to do work.
Potential Energy
Potential energy is the energy
stored for use at a later time.
Examples:
• water behind a dam
• a compressed spring
• chemical bonds in
.gasoline, coal, or food
Kinetic Energy
Kinetic energy is the
energy of matter in
motion.
Examples:
• swimming
• water flowing over a
dam
• working out
• burning gasoline
Heat and Energy
Heat
• is also called thermal energy.
• is associated with the motion of particles.
Adding heat to food increases the motion of the particles, which
makes the food hot.
• Heat is measured in joules or calories.
Examples of Energy Values in Joules
Learning Check
How many calories are obtained from a pat of
butter if it provides 150 J of energy when
metabolized?
Temperature Scales
In science, temperature is
measured in Celsius (oC)
units.
Temperature scales
 are Fahrenheit,
Celsius, and Kelvin.
 have reference points
for the boiling and
freezing points of
water.
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
8
Clicker Time!
Question 1: True or false, a change in
temperature of 10 kelvin is the same as
changing 10◦F?
A) True
B) False
Question 2
Energy that is in motion is what type of energy?
A) Potential
B) Kinetic
Question 3
The volume of a 3 gram block is 6 cm3, what is
it’s density?
a) 18 gcm3
b) 2 cm3/g
c) 0.5 g/cm3
Question 4
Which 5.5 mL block weighs more?
a) Lead (11.3g/mL )
b) Wood (0.75 g/mL)
c) Iron (7.86 g/mL)
d) Gold (19.3 g/mL)
Matter
Matter
 is anything that has mass and occupies space.
 makes up the things we see everyday, such as water, wood,
cooking pans, clothes, and shoes.
 can be classified as a pure substance or mixture.
Mixture
Matter
Pure Substance
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
13
Pure Substances
A pure substance
 has a fixed or constant composition.
 can be classified as an element or compound.
Element – one
type of atom
Pure Substance
Compound – two
or more elements
chemically combined
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
14
Elements
Elements are pure substances
that contain atoms of only
one type.
Examples:
copper (Cu)
lead (Pb)
aluminum (Al)
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
15
Compounds
Compounds contain two or more
elements that are chemically combined
in a definite ratio.
Examples:
salt (NaCl)
table sugar (C12H22O11)
water (H2O)
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
16
Elements in a Compound
Table salt is a compound that contains the elements sodium
and chlorine.
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
17
Mixtures
A mixture is matter that consists of
 two or more substances that are physically mixed, not
chemically combined.
 a composition that is not constant.
Mixtures are
 classified by their composition.
 called homogeneous when they are uniform.
 called heterogeneous when they are not uniform.
Mixtures
Homogeneous
Mixture – Uniform
Heterogeneous
Mixture – Not uniform
Homogeneous Mixtures
In a homogeneous mixture, the
 composition is uniform
throughout, and
 different parts of the mixture are
not visible.
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
19
Heterogeneous Mixtures
In a heterogeneous mixture, the
 composition is not uniform; it
varies from one part of the
mixture to another, and
 different parts of the mixture are
visible.
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
20
Classification of Matter
Matter is organized by its components: elements, compounds, and
mixtures.
Clickers!
Identify each of the following as a pure substance (A) or a
Mixture (B).
A. pasta and tomato sauce
B. aluminum foil
C. helium
D. air
Learning Check
Identify each of the following as a homogeneous (A) or
heterogeneous (B) mixture.
1. hot fudge sundae
2. a clear shampoo
3. sugar water
4. peach pie
Solids
Solids have
• a definite shape.
• a definite volume.
• particles that are close
together in a rigid
pattern.
• particles that vibrate
slowly in their fixed
positions.
Amethyst, a solid, is a purple
form of quartz (SiO2).
Liquids
Liquids have
• a definite volume, but
not a definite shape.
• the same shape as
their container.
• particles that are close
together, but mobile.
• particles that move
slowly in random
directions.
Gases
Gases
• do not have a definite shape.
• do not have a definite
volume.
• take the same shape and
volume as their container.
• have particles that are far
apart.
• are composed of fast moving
particles that have little
attraction to each other.
A Comparison of Solids, Liquids,
and Gases
© 2013 Pearson Education, Inc.
Chapter 2, Section 4
27
Summary of Chemical and Physical
Properties and Changes
Physical Properties
Physical properties
• are observed or measured without affecting
the identity of a substance.
• include shape, physical state, boiling and
freezing points, density, and color of that
substance.
Physical Properties of Copper
Physical Change
A physical change occurs in a substance if there is
 a change in the state.
 a change in the physical shape.
 no change in the identity and composition of the
substance.
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
31
Change of State: Melting and
Freezing
At the melting point,
a solid is converted to
a liquid.
At the freezing point,
a liquid is converted
to a solid.
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
32
Change of State: Evaporation and
Condensation
At the boiling point, a
liquid is converted to
a gas.
At the same
temperature, a gas is
converted to a liquid
as heat is removed.
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
33
Change of State: Sublimation and
Deposition
Sublimation is the
process that describes
the physical change of
a solid directly to a gas.
Deposition is the
process that describes
the physical change of
a gas directly to a solid.
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
34
Chemical Properties and Chemical
Change
Chemical properties describe the ability of a
substance to change into a new substance.
During a chemical change a new substance
forms that has
• a new composition.
• new chemical and physical properties.
Example of Chemical Change
Iron (Fe) nails react with
oxygen (O2) to form rust
(Fe2O3).
Iron
Fe
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
Iron (III) oxide
Fe2O3
36
Clickers!
Classify each of the following as a (A) physical
change or (B) chemical change.
1. __ burning a candle
2. __ ice melting on the street
3. __ toasting a marshmallow
4. __ cutting a pizza
Specific Heat
Specific heat
• is different for different substances.
• is the amount of heat that raises the temperature
of 1 g of a substance by 1 C.
• is represented by the equation,
where ΔT = the change in temperature.
• in the SI system, has units of J/g C.
• in the metric system, has units of cal/g C.
Specific Heats of Some Substances
Calculating Specific Heat
What is the specific heat of a metal if 24.8 g
absorbs 65.7 cal of energy and the temperature
rises from 20.2 C to 24.5 C?
Given
24.8 g
65.7 cal
ΔT = 20.2 C to 24.5 C
Need
Heat Equation
Rearranging the specific heat expression gives the
heat equation:
The amount of heat lost or gained by a substance is
calculated from
• the mass of substance (g),
• the temperature change (T), or
• the specific heat of the substance (cal/g C) or
(J/g C).
Sample Calculation for using Specific
Heat
A hot-water bottle contains 750 g of water
at 65 C. If the water cools to body
temperature (37 C), how many calories of
heat could be transferred to sore muscles?
Given
Need
Calories of heat
transferred
Learning Check
How many kilojoules are needed to raise the
temperature of 325 g of water from 15.0 C to
77.0 C?
Calorimeters
A calorimeter
 is used to calculate the energy value of food.
 contains a reaction chamber and
thermometer in water.
 indicates the amount of heat lost by food by
observing the temperature increase of the
water.
Energy and Nutrition
On food labels, energy is shown as the
nutritional Calorie, written with a capital C.
In countries other than the United States,
energy is shown in kilojoules (kJ).
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
45
Energy Values for 3 Food Types
The energy (caloric) values of food are the
kilojoules or kilocalories obtained from
burning 1 g of a carbohydrate, fat, or
protein.
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
46
Food Nutrition Labels
On packaged foods, the
energy content is listed in
the Nutrition Facts label on
the package, usually in
terms of the number of
Calories for one serving.
Energy Content of Some Foods
Calculating Food Energy Values
How Many Calories are in a Large McDonald’s
Fries?
Energy Requirements
 The amount of energy
needed each day
depends on age,
gender, and level of
physical activity.
 If food intake exceeds
energy use, a person
gains weight.
 If food intake is less
than energy use, a
person loses weight.
© 2013 Pearson Education, Inc.
Chapter 2, Section 2
50
Wednesday
•
•
•
•
Quiz
Lecture on Chapter 3
Do your Pre-lab for this Experiment #1
Lab this Week!!