⚡ Show all working — the AI marks against the AQA mark scheme. Method marks awarded for correct working even if the final answer is wrong.
1 markCollision theoryAQA 8462 style
According to collision theory, for a reaction to occur, particles must:
A Simply collide with each other
B Collide with sufficient energy to overcome the activation energy
C Collide at exactly 180° to each other
D Have identical sizes and shapes
3 marksEffect of temperatureAQA 8462 P2 style
Explain in terms of collision theory why increasing temperature increases the rate of a reaction. (3 marks)
Hint: Cover: more energy → faster movement → more frequent collisions → more exceed activation energy → more successful collisions.
+30 XP
1 markSurface area effectAQA 8462 style
The same mass of calcium carbonate is used in two experiments: one as a large lump, one as a powder. The powder reacts faster. Explain why.
A The powder has less mass than the lump
B The powder has a greater surface area — more particles are exposed to acid — more frequent collisions
C The powder has a different chemical composition from the lump
D The powder produces more heat which speeds up the reaction
4 marksCatalyst explanationAQA 8462 style
Manganese dioxide (MnO₂) acts as a catalyst in the decomposition of hydrogen peroxide: 2H₂O₂ → 2H₂O + O₂. Explain what a catalyst is and how it increases the rate of reaction. (4 marks)
Hint: Define catalyst (increases rate, not used up). Explain mechanism: lower activation energy → more successful collisions. State amount of product is unchanged.
+40 XP
1 markRate graph interpretationAQA 8462 style
A rate experiment produces a graph of volume of gas vs time. A steeper gradient at the start indicates: