Chemistry 25
Chapter 3
Matter and Energy
What Is Matter?
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Chemists study the differences in matter and
how that relates to the structure of matter.
Even though it appears to be smooth and
continuous, matter is actually composed of a
lot of tiny little pieces we call atoms and
molecules.
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Phases (States) of Matter
Phases (States) of Matter
Gas
Liquid
Solid
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Gases
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No/minimal interaction among particles
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The particles have complete freedom from each other.
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Particles have
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There is a lot of empty space between the
particles.
Liquids
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The particles in a liquid
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• The close packing results in liquids
• The ability of the particles to move
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Solids
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The particles in a solid
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The close packing of the particles results in solids being
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The inability of the particles to move around results in
solids
Solids, Continued
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Crystalline solids
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Salt and diamonds.
Amorphous solids
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Plastic and glass.
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Classification of Matter
Atoms and Molecules
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Atoms are the tiny particles that make
up all matter.
In most substances, the atoms are
joined together in units called molecules.
• The atoms are joined in specific geometric
arrangements.
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Structure Determines Properties
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1.
2.
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4.
The properties of matter are determined by the
atoms and molecules that compose it.
Carbon Monoxide
Composed of one carbon atom
and one oxygen atom.
Colorless, odorless gas.
Burns with a blue flame.
Binds to hemoglobin.
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2.
3.
4.
Carbon Dioxide
Composed of one carbon atom
and two oxygen atoms.
Colorless, odorless gas.
Incombustible.
Does not bind to hemoglobin.
Classifications of Matter
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Classification of Pure
Substances
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Elements
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Basic building blocks of matter.
Composed of single type of atom.
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Substances that can be decomposed.
Chemical combinations of elements.
• Although those atoms may or may not be combined into molecules.
Compounds
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Although properties of the compound are unrelated to the properties of the
elements in it!
Composed of molecules that contain two or more different kinds of
atoms.
All molecules of a compound are identical, so all samples of a
compound behave the same way.
Copper—A Pure Substance
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Color is brownish red.
Shiny, malleable, and ductile.
Excellent conductor of heat and
electricity.
Melting point = 1084.62 °C
Density = 8.96 g/cm3 at 20 °C
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Brass—A Mixture
Type
Color
% Cu % Zn Density
g/cm3
MP
°C
Uses
Commercial
bronze
90
10
8.80
1043
door knobs and
grillwork
Jewelry
bronze
87.5
12.5
8.78
1035
costume jewelry
Red
golden
85
15
8.75
1027
electrical sockets,
and fasteners,
eyelets
Cartridge
Common
yellow
70
30
8.47
954
car radiator cores
yellow
67
33
8.42
940
lamp fixtures and
bead chain
Classifications of Matter
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Pure Substance = All samples are made of the same
pieces in the same percentages.
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Salt
Mixtures = Different samples may have the same
pieces in different percentages.
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Salt water
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Pure Substances vs. Mixtures
Pure Substances
Mixtures
All samples have the same
physical and chemical properties.
Different samples may show different
properties.
Constant composition = All
samples have the same pieces in
the same percentages.
Variable composition = Samples
made with the same pure substances
may have different percentages.
Homogeneous.
Homogeneous or heterogeneous.
Separate into components based
on chemical properties.
Separate into components based on
physical properties.
Temperature stays constant while Temperature usually changes while
melting or boiling.
melting or boiling because
composition changes
Practice—Classify the Following
as Pure Substances or Mixtures
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A homogeneous liquid whose temperature stays
constant while boiling.
Granite—a rock with several visible minerals in it.
A red solid that turns blue when heated and
releases water that is always 30% of the solid’s
mass.
A gas that when cooled and compressed, a
liquid condenses out but some gas remains.
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Classification of Pure
Substances
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Substances that cannot be broken down into simpler
substances by chemical reactions are called elements.
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Although those atoms may or may not be combined into molecules.
Substances that can be decomposed are called compounds.
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Basic building blocks of matter.
Composed of single type of atom.
Chemical combinations of elements.
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Although properties of the compound are unrelated to the properties of the
elements in it!
Composed of molecules that contain two or more different kinds of
atoms.
All molecules of a compound are identical, so all samples of a
compound behave the same way.
Most natural pure substances are compounds.
Atoms and Molecules
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Atoms
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Molecules
• Are submicroscopic particles that are the unit
pieces of elements.
• Are the fundamental building blocks of all matter.
• Are submicroscopic particles that are the unit
pieces of compounds.
• Two or more atoms attached together.
• Attachments are called bonds.
• Attachments come in different strengths.
• Molecules come in different shapes and patterns.
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Classifications of Matter
Element
1. Made of one type of atom. (Some
elements are found as multi-atom molecules
in nature.)
2. Combine together to make compounds.
Molecule/Compound
1. Made of one type of molecule, or array of ions.
2. Molecules contain 2 or more different kinds of atoms.
Practice—Classify the Following
as Elements or Compounds
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Chlorine, Cl2
Table sugar, C12H22O11
A red solid that turns blue when heated
and releases water that is always 30% of
the solid’s mass.
A brown-red liquid that, when energy is
applied to it in any form, causes only
physical changes in the material, not
chemical.
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Classification of Mixtures
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Mixtures are generally classified based on
their uniformity.
Homogeneous
• Mixtures that are uniform throughout.
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Also known as
Mixing is on the molecular level.
Heterogeneous
• Mixtures that have regions with different
characteristics.
Classifications of Matter
1. Made of multiple substances, whose
presence can be seen.
2. Portions of a sample have different
composition and properties.
1. Made of multiple substances, but
appears to be one substance.
2. All portions of a sample have the
same composition and properties.
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Properties Distinguish Matter
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Each sample of matter is distinguished by its
characteristics.
The characteristics of a substance are called
its properties.
Some properties of matter can be observed
directly.
Other properties of matter are observed when
it changes its composition.
Properties of Matter
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Physical Properties
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Chemical Properties
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Some Physical Properties
Some Chemical Properties
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Some Chemical and Physical
Properties of Iron
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Physical properties
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Iron is easily oxidized in moist
air to form rust.
When iron is added to
hydrochloric acid, it produces a
solution of ferric chloride and
hydrogen gas.
Iron is more reactive than silver,
but less reactive than
magnesium.
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Chemical properties
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Iron is a silvery solid at room
temperature with a metallic
taste and smooth texture.
Iron melts at 1538 °C and
boils at 4428 °C.
Iron’s density is 7.87 g/cm3.
Iron can be magnetized.
Iron conducts electricity, but
not as well as most other
common metals.
Iron’s ductility and thermal
conductivity are about average
for a metal.
It requires 0.45 J of heat
energy to raise the temperature
of one gram of iron by 1°C.
Decide Whether Each of the
Observations About Table Salt Is a
Physical or Chemical Property
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Salt is a white, granular solid.
Salt melts at 801 °C.
Salt is stable at room temperature, it does not
decompose.
36 g of salt will dissolve in 100 g of water.
Salt solutions and molten salt conduct electricity.
When a clear, colorless solution of silver nitrate is
added to a salt solution, a white solid forms.
When electricity is passed through molten salt, a
gray metal forms at one terminal and a yellowgreen gas at the other.
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Changes in Matter
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Physical changes.
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Chemical changes.
Changes in Matter, Continued
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Physical Changes
Changes in the properties of matter that do not effect its
composition.
• Heating water.
• Raises its temperature, but it is still water.
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Evaporating butane from a lighter.
Dissolving sugar in water.
• Even though the sugar seems to disappear, it can easily
be separated back into sugar and water by evaporation.
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Changes in Matter, Continued
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Chemical Changes
involve a change in the properties of matter that change
its composition.
• A chemical reaction.
• Rusting is iron combining with oxygen to make iron(III)
oxide.
• Burning results in butane from a lighter to be changed
into carbon dioxide and water.
• Silver combines with sulfur in the air to make tarnish.
Is it a Physical or Chemical
Change?
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A physical change results in a different form of
the same substance.
• The kinds of molecules don’t change.
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A chemical change results in one or more
completely new substances.
• The new substances have different molecules
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than the original substances.
You will observe different physical properties
because the new substances have their own
physical properties.
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Phase Changes Are
Physical Changes
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Boiling =
Melting =
Subliming =
Freezing =
Condensing =
Deposition =
State changes require heating or cooling
the substance.
Practice—Classify Each Change
as Physical or Chemical
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Evaporation of rubbing alcohol.
Sugar turning black when heated.
An egg splitting open and spilling out.
Sugar fermenting.
Bubbles escaping from soda.
Bubbles that form when hydrogen
peroxide is mixed with blood.
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Separation of Mixtures
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Separate mixtures based on different physical
properties of the components.
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Physical change.
Distillation
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Filtration
Law of Conservation of Mass
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Antoine Lavoisier
“Matter is neither created nor destroyed
in a chemical reaction.”
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Conservation of Mass
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Total amount of matter remains constant
in a chemical reaction.
• Combustion of 58 grams of butane burns to
form 176 grams of carbon dioxide and 90
grams of water in 208 grams of oxygen
Practice
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A Student Places Table Sugar and Sulfuric Acid
into a Beaker and Gets a Total Mass of 144.0 g.
Shortly, a Reaction Starts that Produces a
“Snake” of Carbon Extending from the Beaker
and Steam Is Seen Escaping. If the Carbon
Snake and Beaker at the End Have a Total
Mass of 129.6 g, How Much Steam Was
Produced?
Video
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Energy
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There are things that do not have mass and
volume.
These things fall into a category we call
energy.
Energy is anything that has the capacity to do
work.
Although chemistry is the study of matter,
matter is effected by energy.
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It can cause physical and/or chemical changes in
matter.
Law of Conservation of Energy
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Kinds of Energy
Kinetic and Potential
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Potential energy
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Water flows because gravity pulls it downstream.
However, the dam won’t allow it to move, so it has to
store that energy.
Kinetic energy
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When the water flows over the dam, some of its potential
energy is converted to kinetic energy of motion.
Some Forms of Energy
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Electrical
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Kinetic energy associated with the flow of electrical charge.
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Heat or Thermal Energy
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Light or Radiant Energy
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Kinetic energy associated with molecular motion.
Kinetic energy associated with energy transitions in an atom.
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Nuclear
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Chemical
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Potential energy in the nucleus of atoms.
Potential energy in the attachment of atoms or because of their
position.
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Converting Forms of Energy
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When water flows over the dam, some of its potential
energy is converted to kinetic energy.
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The movement of the water is kinetic energy.
Along the way, some of that energy can be used to
push a turbine to generate electricity.
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Some of the energy is stored in the water because it is at a
higher elevation than the surroundings.
Electricity is one form of kinetic energy.
The electricity can then be used in your home. For
example, you can use it to heat cake batter you
mixed, causing it to change chemically and storing
some of the energy in the new molecules that are
made.
“Losing” Energy
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If a process was 100% efficient, we
could theoretically get all the energy
transformed into a useful form.
Unfortunately we cannot get a 100%
efficient process.
The energy “lost” in the process is
energy transformed into a form we
cannot use.
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Units of Energy
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Calorie (cal) is the amount of energy
needed to raise one gram of water by 1
°C.
• kcal = energy needed to raise 1000 g of water
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1 °C.
food calories = kcals.
Energy Conversion Factors
Practice
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A candy bar contains 225 Cal of
nutritional energy. How many
joules does it contain?
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Chemical Potential Energy
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The stored energy arises mainly from the
attachments between atoms in the molecules and
the attractive forces between molecules.
When materials undergo a physical change, the
attractions between molecules change as their
position changes, resulting in a change in the
amount of chemical potential energy.
When materials undergo a chemical change, the
structures of the molecules change, resulting in a
change in the amount of chemical potential energy.
Energy Changes and
Chemical Reactions
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Chemical reactions happen most
readily when energy is released during
the reaction.
Molecules with lots of chemical
potential energy are less stable than
ones with less chemical potential
energy.
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Chemical Potential Energy
Chemical Potential Energy
Products
Reactants
Products
Products
Exothermic Processes
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A change results in
An exothermic chemical reaction occurs when
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The excess energy is released into the
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Endothermic Processes
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An endothermic chemical reaction occurs
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The required energy
Temperature Scales
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Fahrenheit scale,
°F.
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Celsius scale, °C.
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Used in the U.S.
Used in all other
countries.
A Celsius degree is
1.8 times larger than a
Fahrenheit degree.
Kelvin scale, K.
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Absolute scale.
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Conversion between Different
Temperature Scales
100 ˚C
373 K
212 ˚F
Boiling
671 R
point water
25 ˚C
298 K
75 ˚F
Room temp 534 R
0 ˚C
273 K
32 ˚F
Melting
point ice
459 R
Boiling
point
oxygen
162 R
-183 ˚C
-269 ˚C
-273˚C
Celsius
90 K
-297 ˚F
4K
0 K -452 ˚F
Kelvin
-459 ˚F
Fahrenheit
BP helium
Absolute
zero
7R
0R
Example
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Convert –25 °C to Kelvins
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Example
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Convert 55° F to Celsius
Example
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Convert 310 K to Fahrenheit
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Practice
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Convert 310 K to
Fahrenheit.
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Convert 0 °F into
Kelvin
Energy and the Temperature of
Matter
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The amount the temperature of an object
increases depends on the amount of heat
energy added (q).
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If you double the added heat energy the temperature
will increase twice as much.
The amount the temperature of an object
increases depending on its mass.
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If you double the mass, it will take twice as much heat
energy to raise the temperature the same amount.
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Heat Capacity
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Heat capacity
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Specific heat
Specific Heat Capacity
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Specific heat
The larger a material’s specific heat is, the more
energy it takes to raise its temperature a given
amount.
Like density, specific heat is a property of the type of
matter.
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It doesn’t matter how much material you have.
It can be used to identify the type of matter.
Water’s high specific heat is the reason it is such a
good cooling agent.
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It absorbs a lot of heat for a relatively small mass.
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Heat Gain or Loss by an Object
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The amount of heat energy gained or
lost by an object depends on 3 factors:
Example
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Calculate Amount of Heat Needed
to Raise Temperature of 2.5 g Ga
from 25.0 to 29.9 °C
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Example
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Calculate Amount of Heat Needed to
Raise Temperature of 2.5 g Ga from
25.0 to 29.9 °C
Practice
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Calculate the Amount of Heat
Released When 7.40 g of Water
Cools from 49° to 29 °C
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Practice
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Calculate the Amount of Heat Released
When 7.40 g of Water Cools from 49°
to 29 °C, Continued
Vocabularies
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Gas, Liquid, Solid
Crystalline/Amorphous
Pure substance/Mixture
Atom/Molecule
Homogeneous/Heteroge
neous
Chemical
property/change/reaction
Physical
property/change/reaction
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Matter
Conservation of mass
Law of Conservation of
Energy
Kinetic/Potential energy
Chemical Potential
energy
Exothermic/Endothermic
processes
Heat capacity/Specific
heat
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