Two identical containers hold the same mixture of nitrogen and hydrogen at the same temperature and pressure. Iron is added to one container. Ammonia forms faster in this container.
How are the collisions between the nitrogen and hydrogen particles affected when iron is added?
A larger fraction of the collisions between the particles is successful.
Collisions occur more frequently, but the fraction that is successful is unchanged.
Each successful collision forms more ammonia, so fewer collisions are needed.
Collisions become less frequent as the iron is used up during the reaction.
122 exam-style questions on OCR GCSE Chemistry 5.2 Controlling reactions, covering 5.2.1 Measuring and interpreting rate of reaction, 5.2.2 Factors affecting rate and collision theory, and 5.2.3 Catalysts, activation energy and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.