Changing the pressure on the reaction
2 marks · HardA chemical reaction between nitrogen and hydrogen gases is taking place in a sealed vessel. The pressure inside the vessel is increased while the temperature remains constant.
Describe and explain what happens to the rate of reaction when the pressure is increased.
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Also accept: The rate of reaction increases because increasing pressure forces gas particles closer together, causing more frequent collisions.
Common mistakes: Saying there is no effect; Only stating 'rate increases' with no explanation
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Marking points
B1 · 1 mark · States that the rate of reaction increases when pressure is increased.
B2 · 1 mark · Explains that gas particles are forced closer together so they collide more frequently.
Worked solution
When the pressure is increased, the rate of reaction increases.
This is because gas particles are squeezed into a smaller volume, so they are closer together and collide more frequently.