3.3 - Particle Model and Pressure

Question 1

Describe the motion of molecules in a gas.

Answer 1

constant random motion.

Question 2

What factor affects the average kinetic
energy of gas molecules?

Answer 2

● The temperature of the substance

Question 3

why does temp do this

Answer 3

● The higher the temperature, the higher
the average kinetic energy of the
molecules

Question 4

What effect does increasing temperature
have on the pressure of a gas when held
at constant volume?

Answer 4

Pressure of the gas will increase as the
temperature increases.

Question 5

Why does pressure increase as
temperature increases (at a constant
volume)?

Answer 5

● Kinetic energy of molecules increases
● Collisions between molecules becomes
more frequent
● Greater rate of change of momentum
● Greater force and therefore pressure

Question 6

If gas A is at a low pressure, and gas B is at a high pressure, what can be said
about the rate of collisions in each gas?

Answer 6

● There are more collisions per second
in gas B than in gas A
● The rate of collisions is higher in B

Question 7

Describe the force that the pressure of a gas exerts on the walls of its container.

Answer 7

● The net force acts at right-angles to
the container’s surface
● The force increases as pressure
increases

Question 8

Explain how increasing the volume of a
gas results in a decrease of pressure

Answer 8

● Molecules become more spread out and so time
between collisions increases
● This reduces the rate of collisions
● Rate of change of momentum decreases, and so
force exerted on container decreases, resulting in
a lower pressure

Question 9

What can be said about the product of
pressure and volume for a fixed mass of
gas at a constant temperature? (Higher)

Answer 9

What can be said about the product of pressure and
volume for a fixed mass of gas at a constant
temperature?
It is constant.

Question 10

What increases when you do work on a
gas?

Answer 10

● The internal energy of the gas
● This can also lead to an increase of
temperature

Question 11

Why does the temperature of air inside a
bike pump increase when it is pumped?

Answer 11

● Work is done on a gas when it is compressed
● Doing work on a gas increases its internal energy,
so also increases the average kinetic energy of
the molecules
● Temperature increases with an increase of
average kinetic energy