Collision model, activation energy, reaction mechanisms and catalysis

Learning objectives

Explain reaction rate using the collision model, requiring collisions with sufficient energy and correct orientation, and relate the fraction of effective collisions to the Maxwell–Boltzmann distribution

Interpret a reaction energy profile, identifying activation energy for the forward and reverse reactions, the enthalpy change and any intermediates in a multi-step reaction

Use the Arrhenius relationship to explain and calculate the effect of temperature on the rate constant, including finding activation energy from the slope of a plot of ln k against 1/T

Evaluate whether a proposed mechanism is consistent with the experimental rate law, checking that the elementary steps sum to the overall equation and that the rate-determining step gives the observed rate law

Distinguish an intermediate from a catalyst in a mechanism, and explain how homogeneous, heterogeneous and enzyme catalysts increase rate by providing an alternative pathway of lower activation energy