(A Level) Rate equations, orders of reaction and catalysis

Learning objectives

Use rate equations of the form rate = k[A]ᵐ[B]ⁿ with orders 0, 1 or 2, deduce the units of the rate constant k, and explain qualitatively how k changes with temperature

Deduce orders of reaction from initial-rates data, from concentration–time graphs (including constant half-life) and from rate–concentration graphs, and construct the rate equation

Calculate k from initial rates or from the half-life of a first-order reaction using k = 0.693/t½

Relate a rate equation to a multi-step mechanism by identifying the rate-determining step, intermediates and catalysts, and suggest a mechanism consistent with a given rate equation

Describe heterogeneous catalysis by adsorption, bond weakening and desorption (Fe in the Haber process; Pt, Pd and Rh in catalytic converters) and homogeneous catalysis by an intermediate that is later regenerated (Fe²⁺/Fe³⁺ in the I⁻/S₂O₈²⁻ reaction; NO₂ in the oxidation of atmospheric SO₂)