Gas Laws Day 2

Bell Ringer

What happens to the air
pressure in your car tires in
the winter?

Multiple Choice

When a cold tire is inflated to a certain pressure and then is warmed up due to friction with the road, the pressure increases. This happens because the

• air molecules hit the walls of the tire less frequently

• rubber in the tires reacts with oxygen in the atmosphere

• air molecules speed up and collide with the tire walls more often

• air molecules diffuse rapidly through the walls of the tire.

Essential Question

Standard

SC.912.P.12.10

• Using the kinetic molecular theory, describe and predict

the behavior of gases and the relationship between
pressure, temperature, number of molecules and volume
(Charles' Law, Boyle's Law, and the Ideal Gas Law).

Multiple Choice

The force of attraction between molecules is ___.

• intermolecular forces

• bridge forces

• chemical bonds

Multiple Choice

Collisions in which particles transfer all their kinetic energy to other particles are called ___.

• elastic

• inelastic

After today
you will be
able to…

Note Time: Kinetic Molecular
Theory
KMT makes three major assumptions about the
particles in a gas:
1. Their particles move in a straight line until

they collide with other particles or the walls

of their container.

2. The motion of the particles is

constant and

random.

3. There are no

attractive or repulsive forces

among the particles.

Multiple Choice

The more energy that particles have, the ___ they move.

• slower

• faster

Note Time: Kinetic Molecular
Theory
Four variables are generally used to
describe a gas.

1.

Pressure (

kPa

, mmHg,

atm

)

2.

Volume (L or mL)

3.

Temperature (always in Kelvin!)

4.

Amount (moles)

Match

Match the following units to their names.

• Pressure

• Volume

• Temperature

• Pressure

• Moles

mmHg

L

K

atm

mol

• mmHg

• L

• K

• atm

• mol

Factors Affecting Gas Pressure

Effect of adding or removing gas:

•

When the amount of gas in each container is

increased, pressure increases.
•Example: Doubling amount of gas

= gas particle

2x Amount of gas,

2x Pressure

Factors Affecting Gas Pressure

•More particles means more
collisions

, which means more

pressure!
•This is a direct relationship:

If

the number of particles double,

pressure doubles.

Factors Affecting Gas Pressure

Effect of changing volume of container:

•

When the volume of a gas is decreased (for a

given amount of gas) pressure increases.
•Example: Decreasing volume by half

= gas particle

½ Volume,
2x Pressure

Multiple Choice

If the pressure in a balloon remains constant what happens to the balloon's volume as the temperature of the air increases?

• the volume decreases and the balloon shrivels up or shrinks

• the volume increases and the balloon expands

• the volume stays the same and the balloon stays the same size

Factors Affecting Gas Pressure

•

Particles are closer together in a

container which means more
collisions which really means
more pressure!
•This is an indirect relationship:

If

the volume is halved, pressure is

doubled and vice

-

versa.

Factors Affecting Gas Pressure

Effect of changing temperature of a gas:

•

When the temperature of a gas increases the

particles have more KE, and pressure

increases.
•Example: Doubling temperature

= gas particle

298K

596K

2x Temperature,

2x Pressure

Factors Affecting Gas Pressure

•The particles move faster when
heated and

strike the walls of

the container with more force, so

the pressure builds.
•This is a direct relationship:

If

the temperature is doubled,

pressure is doubled and vice

-

versa.

Real-World Application:
Aerosol Cans

A gas in a sealed container can generate an
enormous amount of pressure when heated.
• That’s why all labels on aerosol cans say “DO NOT

STORE ABOVE 120°F.”

• Even “empty” aerosol cans still have some gas in

them, so they will explode if thrown into a fire.

• It is also wise to not store cans at temperatures

that will freeze the substances in them.
Freezing causes the substance to expand and will
puncture the can.

Multiple Choice

If a hairspray can is heated, what can be expected of the pressure of the gas inside the can?

• The pressure will increase

• The pressure will decrease

• The pressure will remain constant

• The pressure will equalize

Multiple Choice

What is 50 °C in Kelvin?

• 223.15

• 323.15

• 100.15

• 50.15

Multiple Choice

Charles' Law States...

• As Pressure goes up volume goes down

• As Pressure goes up temperature goes up

• As Volume goes up temperature goes up 

• As Pressure goes down volume goes down 

Assignment

• Complete the virtual laboratory