Chemical Kinetics
Unit III. Covers Rate of reaction; Rate law, order and molecularity; Integrated rate equations; Temperature and rate.
About this unit
Chemical kinetics deals with how fast reactions go and the factors that control their speed. While thermodynamics tells us whether a reaction can happen, kinetics tells us how quickly it happens and by what path. The unit covers measuring rates, writing rate laws, using integrated rate equations for zero- and first-order reactions, and explaining the effect of temperature and catalysts through activation energy and collision theory.
Key ideas
- Average and instantaneous rate, expressed in mol L⁻¹ s⁻¹.
- Rate law, rate constant and its units.
- Order (experimental) versus molecularity (theoretical, for elementary steps).
- Integrated rate equations and half-life for zero- and first-order reactions.
- Pseudo first-order reactions.
- Arrhenius equation, activation energy, effect of catalysts and collision theory.
How to prepare
Memorise the integrated rate equations, half-life expressions and units of k for different orders. Practise numericals on first-order reactions (time for a given fraction to react, half-life) and on the two-temperature form of the Arrhenius equation, using logarithms carefully. Be able to tell order from molecularity and to read rate laws from given data.
Topics in this chapter
Rate of reaction
Average and instantaneous rate and the factors affecting it.
5 questionsRate law, order and molecularity
Rate law, rate constant, order and molecularity.
5 questionsIntegrated rate equations
Zero- and first-order reactions, half-life and pseudo first-order reactions.
5 questionsTemperature and rate
Arrhenius equation, activation energy and collision theory.
5 questions