Chapter 8

If the partial pressure of helium is twice the partial pressure of oxygen, what do you know about the number of helium atoms compared to the number of oxygen molecules? Explain.

• They are equal because a diatomic particle will exert the average pressure against the container's walls, which is half the pressure exerted by an atom.

• The number of He

  atoms is four times larger than the number of O2

  molecules because a diatomic particle will exert the average pressure against the container's walls, which is twice the pressure exerted by an atom.

• The number of He

  atoms is two times larger than the number of O2

  molecules because each particle (an atom or a molecule) will exert the same average pressure against the container's walls.

• The number of He

  atoms is 16 times larger than the number of O2

  molecules because He

  's molecular mass is eight times smaller.

The force of gas particles against the walls of a container is called ________.

• density

• quantity of gas

• 
  volume

• 
  pressure

• 
  temperature

Pressure of a gas increases with increasing temperature.

According to kinetic molecular theory, 

• at a higher temperature, gas particles have smaller kinetic energy.

• at a higher temperature, the number and force of collisions against the walls of the container is greater.

• the attractive forces between the particles of a gas increase with temperature.

• as temperature increases, the concentration of gas molecules in a container increases.

Gas particles fill a container of any size.

According to kinetic molecular theory, 

• 
  the actual volume occupied by gas molecules is extremely small and can fit in a container of any size.

• the repulsive forces between the particles of a gas are strong; thus, particles tend to be as far apart as possible.

• the attractive forces between the particles of a gas are very small and cannot hold the particles together.

• particles of a gas move randomly; thus, the distances between the particles are random values.

Gases have low densities.

According to kinetic molecular theory, 

• gases consist of small particles that have small masses.

• density depends on the path of motion of the particles; thus, the straight paths taken by gases result in low densities.

• although distances between gas particles are usually small, the particles are very light.

• gas particles are very far apart, meaning that the mass of a gas in a certain volume is very small.

The balloon is put into a chamber where the pressure is less than the atmospheric pressure.

• A

• B

• C

• A and B

• B and C

Which of the following statements describe the pressure of a gas?

• 0.11 MPa
  

• 
  28.8 lb/in2
  

• force/area

• 0.5 lblb of N2
  

• the determining factor of the kinetic energy of gas particles

A temperature of 125 °C is the same as ________.

• 398 K

• 
  530. K

• 273 K

• 257 K

• 
  -148 K

The kinetic energy of a gas sample is directly proportional to the Kelvin temperature of the gas.

• True

• False

What happens to the volume of a bicycle tire or a basketball when you use an air pump to add air?

• The volume decreases.

• The volume increases.

• The volume does not change.