Rate of reaction
Edexcel GCSE Chemistry revision on Rate of reaction. Aligned to the Pearson Edexcel GCSE Chemistry 1CH0 specification. This bank has 8 practice questions on this topic.
Sample questions (3 of 8)
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Question 1
Which factor does NOT affect the rate of a chemical reaction?
- A) Temperature
- B) Surface area
- C) Concentration
- D) Colour of the reactants
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Answer: Colour of the reactants
Rate-affecting factors: TEMPERATURE (hotter = particles move faster = more frequent + harder collisions), CONCENTRATION (more reactant per volume = more collisions), SURFACE AREA (more exposed surface = more particles can react), PRESSURE (gases - same as concentration), CATALYST (lowers activation energy).
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Question 2
Increasing the temperature of a reaction increases the rate because...
- A) Particles get smaller
- B) Particles move faster + collide more often AND with more energy
- C) Bonds become weaker
- D) Volume decreases
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Answer: Particles move faster + collide more often AND with more energy
Two effects: (1) particles move faster -> more collisions per second. (2) More energy per collision -> more particles exceed activation energy -> more SUCCESSFUL collisions. Effect 2 is usually bigger. A rough rule: rate roughly DOUBLES per 10C rise (for typical organic reactions).
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Question 3
A catalyst speeds up a reaction by...
- A) Being used up
- B) Providing an alternative pathway with a lower activation energy
- C) Heating the reactants
- D) Adding mass to the mixture
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Answer: Providing an alternative pathway with a lower activation energy
Catalysts: NOT used up in the reaction (can be recovered + reused), provide an alternative route with lower activation energy. More particles have enough energy to react -> faster rate. Doesn't change the overall energy change or the equilibrium position - just the SPEED. Examples: iron in the Haber process, platinum in catalytic converters, enzymes (biological catalysts).
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5 more questions on Rate of reaction — plus mistakes tracking and spaced repetition across the whole Chemistry spec.