Topic Menu

Cyber-chess a chess instruction site

GCSE Questions: Kinetic Theory - Gases

Q4.

(a) The above photo shows balloons filled with helium gas.

Tick two of the statements below that correctly describe the movement of the gas particles in a helium filled balloon.

The particles all move in a predictable way.  
The particles move at the same speed.  
The particles move in circular paths.  
The particles move in random directions.
The particles move with a range of speeds.
The particles vibrate about fixed positions.  

[2 marks]

(b) The pressure of a helium in the balloon is 100,000 Pa.

The volume of the balloon is 0.030 m3 .

The balloon is compressed at a constant temperature causing the volume to decrease to 0.025 m3 .

No helium leaves the balloon.

Calculate the new pressure in the balloon.

At constant temperature:

P1V1 = P2 V2

100,000 x 0.030 = P2 x 0.025

P2= 100,000 x 0.030/0.025

P2= 120,000 Pa

[4 marks]

(c) The temperature of the helium in the balloon was increased.

The mass and volume of helium in the balloon remained constant.

Explain why the pressure exerted by the helium inside the balloon would increase.

At a higher temperature particles would have a higher mean kinetic energy. Therefore there would be an increased number of collisions with the walls of the balloon per second. The change in momentum of those particles as they collided with the balloon material would result in greater forces in a given area on the balloon - pressure is force/area so pressure would increase.

[4 marks]

[10 Marks TOTAL]