Chemical kinetics — WJEC A-Level Chemistry
In summary: Chemical kinetics is a key topic in WJEC A-Level Chemistry. Key exam tip: Ensure you can derive the units for the rate constant k for any given order of reaction
Exam Tips for Chemical kinetics
- Ensure you can derive the units for the rate constant k for any given order of reaction
- Practice calculating activation energy from the Arrhenius equation using logarithmic forms
- Be prepared to interpret concentration-time and rate-concentration graphs to determine reaction order
- Always link the rate equation to the mechanism: the rate-determining step involves the species present in the rate equation
Common Mistakes
- Confusing the rate-determining step with the overall reaction stoichiometry
- Incorrectly applying units to rate constants for different orders of reaction
- Misinterpreting the Arrhenius plot (slope and intercept)
- Failing to correctly identify the rate-determining step from a proposed mechanism
Marking Points
- Principles of measuring reaction rate by sampling and quenching
- Determination of reaction order from experimental results
- Application of the general rate equation
- Concept and identification of the rate-determining step
- Link between reaction kinetics and reaction mechanism
- Use of the Arrhenius equation to find activation energy and frequency factor
- Effect of temperature and catalysts on the rate constant
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