Ch. 11 Gases

Chapter 11 - Gases

By Nicole Woltschlaeger

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What do you already know about gases?

The actual volume occupied by gas molecules is very small compared to the volume the gas occupies.

A gas consists of small particles (atoms or molecules) that move randomly with high velocities

The attractive forces between particles of a gas are usually very small.

Kinetic Molecular Theory of Gases

The average kinetic energy of gas molecules is proportional to the Kelvin temperature.

Kinetic Molecular Theory of Gases

​Gas particles are in constant motion, moving rapidly in straight paths

Multiple Choice

Which state of matter has particles with the lowest average kinetic energy?

• Solid

• Liquid

• Gas

Multiple Choice

Temperature is a direct measure of:

• The density of the particles within a substance.

• The average speed of the particles within a substance.

• How often the particles collide with the walls of their container.

Multiple Choice

To make a solid become a liquid, you must increase its________________.

• mass
• density
• kinetic energy
• potential energy

Multiple Choice

Gas particles move around at __________ speeds. 

• low
• slow
• high
• unknown

Multiple Select

The slower the particles in a substance move,

• the colder it is.
• the warmer it is.
• the more kinetic energy it has.

• the less kinetic energy it has.

Multiple Choice

Which is NOT an assumption made by the kinetic molecular theory of gases?

• Gas particles are small and take up little volume
• Particles travel in constant, random, straight-line motion until colliding
• When particles collide, their total kinetic energy is decreased
• Particles do not attract or repel each other

Pressure, P

When gas particles strike the walls of their container, they exert pressure.

If the gas is heated, the molecules move faster and strike the walls of the container more often with increased force, increasing the pressure.

the pressure exerted by a column of air from the top of the atmosphere to the surface of the Earth.


~1 atmosphere (atm) at sea level.

Atmospheric Pressure