Chapter 20 - Gases

Question 1

What is brownian motion?

Answer 1

The random and unpredictable motion of particles in a fluid caused by molecules of the surrounding substance colliding at random with the particles.
(e.g. collision between air and smoke particles)

Question 2

What is the kinetic theory of gases?

Answer 2

A model which describes a gas as a large number of submicroscopic particles which are in constant, rapid, random motion occasionally undergoing random elastic collisions with other particles and the enclosing walls of the container. (i.e. the gas is assumed to be an ideal gas. For an ideal gas internal energy is only the kinetic
energy of the atoms.).

Question 3

The gas laws are empirical in nature (come from experiments) whereas the kinetic theory model arises from theory.

Answer 3

The gas laws are empirical in nature (come from experiments) whereas the kinetic theory model arises from theory.

Question 4

What is Boyle’s law?

Answer 4

For constant temperature and mass:
pV = constant
p1V1 = p2V2
p ∝ 1/V

Question 5

What is Charles’ law?

Answer 5

For constant pressure and mass:
V/T = constant
V1/T1 = V2/T2
V ∝ T

Question 6

What is the pressure law?

Answer 6

For constant volume and mass:
p/T = constant
p1/T1 = p2/T2
p ∝ T

Question 7

What is the combined gas law?

Answer 7

pV/T = constant
p1V1/T1 = p2V2/T2

Question 8

Describe the following equation, W =pΔV.

Answer 8

When a gas expands, work must be done by the gas to increase the volume of the container.

Question 9

What is the equation for the internal energy of an ideal gas?

Answer 9

3NkT/2
or
3nRT/2

Question 10

Brownian motion is evidence for the…

Answer 10

Brownian motion is evidence for the existence of atoms (as they explained what smoke particles were colliding with).