12.2 Pressure Law

Question 1

What relationship does the pressure law describe?

Answer 1

Relationship between pressure and temperature

Question 2

What is the relationship between pressure and temperature

Answer 2

They’re directly proportional

Question 3

What has to be fixed to analyse pressure and temperature?

Answer 3

Volume and mass

Question 4

What does a graph of pressure against temperature look like? if temperature is in kelvin

Answer 4

Straight line through the origin.

Question 5

What is the pressure law numerically?

Answer 5

p = kt 
p/t = k

Question 6

What does the graph of pressure against temperature look like? if temperature is in celsius

Answer 6

Straight line starting from -273 at x axis

Question 7

Why does temperature increase with pressure>?

Answer 7

Higher temperature means molecules gain kinetic energy, so that they move faster. If the volume stays constant then molecules collide more often and at higher speed so pressure will increase.

Question 8

What are the rules for working with this relationship? in terms of calculations

Answer 8

• p is the TOTAL pressure

- T must be in Kelvin

Question 9

Equation for pressure law?

Answer 9

p1/t1 = p2/t2

Question 10

Why is this the equation?

Answer 10

As they both equal k, the constant hence they must be equal to each other as long as mass and volume are kept constant

Question 11

What setup would we use to investigate the pressure law?

Answer 11

A beaker placed in cold water. A thermometer in water, gas in beaker and a tube from beaker leading to pressure gauge. There is also a heating source

Question 12

What is one thing we have to make sure is done about tube connecting beaker to pressure gauge?

Answer 12

It is as short and as thinnest as possible. This is because volume inside needs to be reduced to minimum as air will not be the same temperature as in the flask.

Question 13

Describe this practical?

Answer 13

Initially the water is made cold by putting ice into it in order to get the lowest staring temperature. The pressure and corresponding temperature are recorded up to the boiling point of water. Time must be given to allow air in beaker to reach temperature of water (done by turning the heating down). Also the water is stirred throughout to allow equal distribution of temperature.

Question 14

At zero pressure and hence volume we get what?

Answer 14

Absolute zero