14.1
Properties of Gases
A soccer ball properly
inflated will rebound faster
and travel farther than an
under-inflated ball. If the
pressure is too high, the
ball may burst when it is
kicked. We will study the
variables that affect the
pressure of a gas.
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14.1
Properties of Gases >
Chemistry
Temperature
Matter
Rates of
Effusion and
Effusion
Pressure
Gas
Density
Volume
Moles
Molar Mass
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14.1
Properties of Gases > Compressibility
Compressibility
Why are gases easier to compress than
solids or liquids are?
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14.1
Properties of Gases > Compressibility
Compressibility is a measure of how much the
volume of matter decreases under pressure.
When a person collides with an inflated airbag,
the compression of the gas absorbs the energy
of the impact.
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14.1
Properties of Gases > Compressibility
Gases are easily compressed because of
the space between the particles in a gas.
• The distance between particles in a gas is
much greater than the distance between
particles in a liquid or solid.
• Under pressure, the particles in a gas are
forced closer together.
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14.1
Properties of Gases > Compressibility
At room temperature, the distance between
particles in an enclosed gas is about 10 times
the diameter of a particle.
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14.1
Properties of Gases > Factors Affecting Gas Pressure
Factors Affecting Gas Pressure
What are the three factors that affect gas
pressure?
•
Amount of Gas
•
Volume
•
Temperature
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14.1
Properties of Gases > Factors Affecting Gas Pressure
Four variables are generally used to describe a
gas. The variables and their common units are
• pressure (P) in kilopascals
• volume (V) in liters
• temperature (T) in kelvins
• the number of moles (n).
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14.1
Properties of Gases > Factors Affecting Gas Pressure
Amount of Gas
You can use kinetic theory to predict and explain
how gases will respond to a change of
conditions. If you inflate an air raft, for example,
the pressure inside the raft will increase.
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14.1
Properties of Gases >
Heat
Energy transferred due to differences in temperature
Temperature
Measure of the average kinetic energy of particles
composing a material
Pressure
Force per unit area
Volume
The amount of space a material occupies
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14.1
Properties of Gases > Factors Affecting Gas Pressure
Collisions of particles with the inside walls of the
raft result in the pressure that is exerted by the
enclosed gas.
If you increase the number of particles it will
increase the number of collisions, which is why
the gas pressure increases.
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14.1
Properties of Gases > Factors Affecting Gas Pressure
If the gas pressure increases until it exceeds the
strength of an enclosed, rigid container, the
container will burst.
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14.1
Properties of Gases > Factors Affecting Gas Pressure
Aerosol Spray Paint
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14.1
Properties of Gases > Factors Affecting Gas Pressure
Volume
You can raise the pressure exerted by a
contained gas by reducing its volume. The more
a gas is compressed, the greater is the pressure
that the gas exerts inside the container.
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14.1
Properties of Gases > Factors Affecting Gas Pressure
When the volume of the container is halved, the
pressure the gas exerts is doubled.
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14.1
Properties of Gases > Factors Affecting Gas Pressure
Temperature
An increase in the temperature of an enclosed
gas causes an increase in its pressure.
As a gas is heated, the average kinetic energy of
the particles in the gas increases. Faster-moving
particles strike the walls of their container with
more energy.
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14.1
Properties of Gases > Factors Affecting Gas Pressure
When the Kelvin temperature of the enclosed
gas doubles, the pressure of the enclosed gas
doubles.
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14.1 Section Quiz.
Assess students’ understanding
of the concepts in Section 14.1.
Continue to:
-or-
Launch:
Section Quiz
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14.1 Section Quiz.
1. Compared to liquids and solids, gases are
easily compressed because the particles in a
gas
a. attract each other.
b. are spaced relatively far apart.
c. are very small.
d. repel each other.
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14.1 Section Quiz.
2. Gas pressure is affected by
a. temperature, volume, and the amount of
the gas.
b. temperature, volume, and the molar mass
of the gas.
c. phase diagram, volume, and the size of the
container.
d. temperature, phase diagram, and the mass
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14.1 Section Quiz.
3. For gases, the SI units for volume (V),
pressure (P), and temperature (T) are,
respectively,
a. liters, kilopascals, and °C.
b. liters, kilopascals, and kelvins.
c. cm3, kilopascals, and kelvins.
d. liters, atmospheres, and °C.
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The Gas Laws
This hot air balloon was
designed to carry a
passenger around the
world. You will study some
laws that will allow you to
predict gas behavior under
specific conditions, such
as in a hot air balloon.
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Boyle’s Law: Pressure and Volume
Boyle’s Law: Pressure and Volume
How are the pressure, volume, and temperature
of a gas related?
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Boyle’s Law: Pressure and Volume
If the temperature is constant, as the
pressure of a gas increases, the volume
decreases.
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Boyle’s Law: Pressure and Volume
a. Boyle’s law states that for a given mass of
gas at constant temperature, the volume of
the gas varies inversely with pressure.
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Boyle’s Law: Pressure and Volume
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Boyle’s Law: Pressure and Volume
Simulation 15
Examine the relationship between gas, volume
and pressure.
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14.1
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14.1
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14.1
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14.1
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for Sample Problem 14.1
Problem Solving 14.8
Solve Problem 8 with the
help of an interactive
guided tutorial.
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