Long answer·Standard multi-step (3/5)·No calculator
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
A reaction is slow at room temperature but becomes much faster when a catalyst is added. The same products are formed, and the heat of reaction is unchanged.
Total: 4 marks
(a) Explain how the catalyst increases the rate. (1 mark)
(b) State whether activation energy increases or decreases. (1 mark)
(c) State whether changes. (1 mark)
(d) Explain the answer to part (c). (1 mark)
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