Matter and Energy
Chapter 3
1
Properties
•
Characteristics of the substance under
observation
•
Properties can be either
directly observable or
the manner something interacts with other
substances in the universe
2
Universe Classified
• Matter is the part of the universe that
has mass and volume
• Energy is the part of the universe that
has the ability to do work
• Chemistry is the study of matter
– The properties of different types of matter
– The way matter behaves when influenced
by other matter and/or energy
3
Properties of Matter
• Physical Properties are the characteristics of
matter that can be changed without changing
its composition
– Characteristics that are directly observable
• Chemical Properties are the characteristics
that determine how the composition of matter
changes as a result of contact with other
matter or the influence of energy
• Characteristics that describe the behavior of
matter
4
Classify Each of the following as
Physical or Chemical Properties
The boiling point of ethyl alcohol is 78°C.
Diamond is very hard.
Sugar ferments to form ethyl alcohol.
5
Classify Each of the following as
Physical or Chemical Properties
The boiling point of ethyl alcohol is 78°C.
– Physical property – describes inherent characteristic
of alcohol – boiling point
Diamond is very hard.
– Physical property – describes inherent characteristic
of diamond – hardness
Sugar ferments to form ethyl alcohol.
– Chemical property – describes behavior of sugar –
forming a new substance (ethyl alcohol)
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States of Matter
• solid, liquid, gas
State
Solid
Liquid
Gas
Shape
Keeps
Shape
Takes
Shape of
Container
Takes
Shape of
Container
Volume
Compress
Flow
Keeps
Volume
Keeps
Volume
No
No
No
Yes
Takes
Volume of
Container
Yes
Yes
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Liquid water
takes the
shape of its
container.
Changes in Matter
• Physical Changes are changes to matter that
do not result in a change the fundamental
components that make that substance
– State Changes – boiling, melting, condensing
• Chemical Changes involve a change in the
fundamental components of the substance
– Produce a new substance
– Chemical reaction
– Reactants  Products
9
Classify Each of the following as
Physical or Chemical Changes
Iron metal is melted.
Iron combines with oxygen to form rust.
Sugar ferments to form ethyl alcohol.
10
Classify Each of the following as
Physical or Chemical Changes
Iron is melted.
– Physical change – describes a state change, but the
material is still iron
Iron combines with oxygen to form rust..
– Chemical change – describes how iron and oxygen
react to make a new substance, rust
Sugar ferments to form ethyl alcohol.
– Chemical change – describes how sugar forms a new
substance (ethyl alcohol)
11
Elements and Compounds
• Substances which can not be broken down
into simpler substances by chemical reactions
are called elements
• Most substances are chemical combinations
of elements. These are called compounds.
– Compounds are made of elements
– Compounds can be broken down into elements
– Properties of the compound not related to the
properties of the elements that compose it
– Same chemical composition at all times
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Classification of Matter
Matter
Pure Substance
Constant Composition
Homogeneous
Mixture
Variable Composition
• Homogeneous = uniform throughout, appears to be one
thing
– pure substances
– solutions (homogeneous mixtures)
• Heterogeneous = non-uniform, contains regions with
different properties than other regions
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Pure Substances vs. Mixtures
• Pure Substances
– All samples have the same physical and chemical properties
– Constant Composition  all samples have the same
composition
– Homogeneous
– Separate into components based on chemical properties
• Mixtures
– Different samples may show different properties
– Variable composition
– Homogeneous or Heterogeneous
– Separate into components based on physical properties
• All mixtures are made of pure substances
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Identity Each of the following as a
Pure Substance, Homogeneous
Mixture or Heterogeneous Mixture
Gasoline
A stream with gravel on the bottom
Copper metal
15
Identity Each of the following as a
Pure Substance, Homogeneous
Mixture or Heterogeneous Mixture
Gasoline
– a homogenous mixture
A stream with gravel on the bottom
– a heterogeneous mixture
Copper metal
– A pure substance (all elements are pure substances)
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Separation of Mixtures
• Separate mixtures based on different physical
properties of the components
– Physical change
Different Physical Property
Technique
Boiling Point
Distillation
State of Matter
(solid/liquid/gas)
Adherence to a Surface
Filtration
Chromatography
Volatility
Evaporation
17
Energy and Energy Changes
• Capacity to do work
– chemical, mechanical, thermal,
electrical, radiant, sound, nuclear
• Energy may affect matter
– e.g. raise its temperature, eventually
causing a state change
– All physical changes and chemical
changes involve energy changes
18
Heat
•
Heat: a flow of energy due to a temperature
difference
1. Exothermic = A process that results in the
evolution of heat.
• Example: when a match is struck, it is an
exothermic process because energy is
produced as heat.
2. Endothermic = A process that absorbs
energy.
• Example: melting ice to form liquid water is an
endothermic process.
19
Units of Energy
• One calorie is the amount of energy needed to
raise the temperature of one gram of water by 1°C
– kcal = energy needed to raise the temperature of 1000 g
of water 1°C
• joule
– 4.184 J = 1 cal
• In nutrition, calories are capitalized
– 1 Cal = 1 kcal
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Example - Converting Calories to
Joules
Convert 60.1 cal to joules
1 cal  4.184 joules
4.184 J
60.1cal 
 251J
1 cal
21
Energy and the Temperature of
Matter
• The amount the temperature of an object
increases depends on the amount of heat
added (Q).
– If you double the added heat energy the
temperature will increase twice as much.
• The amount the temperature of an object
increases depends on its mass
– If you double the mass it will take twice as much
heat energy to raise the temperature the same
amount.
22
Specific Heat Capacity
• Specific Heat (s) is the amount of
energy required to raise the
temperature of one gram of a substance
by one Celsius degree
J
By definition , the specific heat of water is 4.184
g C
Amount of Heat = Specific Heat x Mass x Temperature Change
Q = s x m x T
23
Example – Calculate the amount of
heat energy (in joules) needed to raise
the temperature of 7.40 g of water
from 29.0°C to 46.0°C
JJ
Specific Heat of Water = 4.184
gg-CC
Mass = 7.40 g
Temperature Change = 46.0°C – 29.0°C = 17.0°C
Q = s x m x T
J
Heat  4.184
 7.40g  17.0C  526 J
g C
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Example – A 1.6 g sample of metal that
appears to be gold requires 5.8 J to raise
the temperature from 23°C to 41°C.
Is the metal pure gold?
Q  s  m  T
Q
s
m  T
T  41C - 23C  18C
5.8 J
J
s
 0.20
1.6 g x 18C
g C
Table 3.2 lists the specific heat of gold as 0.13
Therefore the metal cannot be pure gold.
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