5.18

5.17 Demo

02 November 2011

19:56

Cloud formation

·         Place a little water in the bottom of a 1½ litre plastic bottle

·         Squeeze a few times

·         Introduce a small amount of smoke

·         Squeeze and release several times

·         When you squeeze, the cloud disappears; when you release, the cloud reforms

 

 

Explanation

·         When the pressure increases the temperature increases and vica versa

·         The smoke particles are nucleating sites on which the water can condense

 5.18 Question

07 November 2011

15:08

Collins, p.116

 p₁/T₁=p₂/T₂

3/293= p₂/328

(3/293)x328=p₂

3.36=p₂

p₂=3.36bar

a.              If we cool the gas in a rigid, sealed tin can, what happens to the pressure inside the can? (1 mark)

The pressure decreases

b.             Explain your answer to part a. by using the Kinetic Theory (4 marks)

·         The particles will have less energy

·         Therefore less average kinetic energy

·         Which means that the pressure will decrease