Learning objective
Use half-life evidence for first-order reactions.
Read the explanation, check the common trap, then practise with flashcards and questions.
At a glance
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Flashcards
0
Questions
Topic
Rate equations (A-level only)
Subtopic
Rate equations and orders (A-level only)
Study support
Understand this objective
Quick explanation
Use half-life evidence for first-order reactions
- This point belongs to Rate equations (A-level only), especially Rate equations and orders (A-level only).
- You need to be able to use half-life evidence for first-order reactions.
- The key ideas to know are half-life and order.
- Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.
Key concepts
Why it matters
This objective helps connect Rate equations and orders (A-level only) to exam-style questions, flashcards, and revision notes for Rate equations (A-level only).
Quick student answer
Which of the following statements is true for a first-order reaction?
Direct answer
The half-life is constant and independent of concentration.
Key terms
- Rate equation: An equation that relates the rate of a reaction to the concentration of reactants, each raised to a power corresponding to their order in the reaction.
- Order of reaction: The power to which the concentration of a reactant is raised in the rate equation, indicating how the rate is affected by changes in concentration.
Common trap
Confusing first-order reactions with second-order reactions: Remember that for first-order reactions, the half-life is constant, while for second-order reactions, the half-life depends on the initial concentration.
Related questions
Try this as a practice card
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Flashcard prompts
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Revision tools
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Flashcards0 linked cards
Practice Questions0 linked questions
Revision notestopic notes
Open the full topic revision notes when you are ready to review this objective in context.
Open revision notesRelated learning objectives
- Deduce orders of reaction from initial rate data.
Rate equations and orders (A-level only)
- Write rate equations using experimentally determined orders.
Rate equations and orders (A-level only)
- Calculate rate constants and their units.
Rate equations and orders (A-level only)
- Interpret concentration-time graphs.
Rate equations and orders (A-level only)
- Explain the rate-determining step in a mechanism.
Mechanisms and rate-determining steps (A-level only)