Chapter 15: Ideal Gases

Question 1

What is Avogadro’s constant

Answer 1

the number of atoms there are in one mole of a substance

Question 2

Key Assumptions in the kinetic theory of gases

Answer 2

• large number of molecules in a random, rapid motion
• particles are negligibly small compared to the total volume of the gas
• all collisions are perfectly elastic
  time taken for a collision is negligible compared to time between collisions
• between collisions there are no forces between particles

Question 3

Why do gases exert a pressure on a container they are in?

Answer 3

• gas particles collide with the surface of the container
• the container exerts a force onto the particles to change their direction. The particles exert an equal and opposite force on the container
• pressure is force applied per unit area

Question 4

What is an ideal gas?

Answer 4

• gas molecules do not interact with each other
• the molecules are perfectly spherical

Question 5

Ideal gas equation

Answer 5

pV = nRT

Question 6

Boyle’s Law

Answer 6

pressure is inversely proportional to volume, providing temperature is constant

Question 7

How are pressure and temperature of a gas related?

Answer 7

directly proportional

Question 8

Use the kinetic theory of gases to explain why a temperature increase leads to an increase in pressure

Answer 8

• particles have more kinetic energy
• more kinetic energy means a greater change in momentum during collisions with the container. There are also more frequent collisions.
• change in momentum is proportional to the force applied, and therefore pressure

Question 9

Root mean square speed

Answer 9

The square root of the mean of the squares of the speed of the molecule

Question 10

What does the area under a Maxwell-Boltzmann curve represent?

Answer 10

total number of particles

Question 11

How does the Maxwell-Boltzmann curve change if the temperature of the gas increases

Answer 11

The average particle speed, and maximum particle speed both increase (curve shifts to the right)
The curve becomes lower and more spread out

Question 12

What is the average kinetic energy of a particle in an ideal gas equal to?

Answer 12

1.5kT

Question 13

TRUE OR FALSE: The internal energy of an ideal gas is proportional to absolute temperature

Answer 13

TRUE
An ideal gas has no potential energy, meaning internal energy is proportional to kinetic energy