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Kinetics from enzymes to polymers (CH2210)

Aims

The aim of this module is to develop many aspects of kinetics introduced previously, to the level where the complex kinetics encountered in the laboratory can be treated mathematically. Complex sequences of elementary reactions, competing reactions and chain reactions will be considered, together with aspects of the kinetics of polymerisation.

General description

The empirical reaction rate theory will be developed further to consider complex processes which involve more than a single reaction step. Simple mechanisms will be used to introduce these ideas. The concepts of the rate determining step and the steady state approximation will be described in detail and illustrated with many examples e.g. enzymes and Lindemann theory. Chain reactions will be discussed and their practical applications in explosions and radical reactions described. The discussion will then be developed to consider reactions in different phases and at the interface between phases. Heterogeneous reactions involving surface adsorption and catalysis will be explored and compared with homogeneous processes. Finally ’perturbation from equilibrium’ will be used to show how this approach may be used to study kinetics.

Syllabus content

Complex homogeneous reactions :

Rate laws of elementary reactions, simple mechanisms - consecutive and parallel unimolecular; reversible unimolecular processes. Approximate solutions to rate equations - steady-state and equilibrium approximations. Rate and equilibrium approximations. Enzyme kinetics.

Diffusion controlled reactions - Fick’s Laws.

Polymerisation kinetics :

Free radical - initiation, chain transfer, conventions. Ionic polymerisation – molar mass control. Copolymerisation - composition drift, reactivity ratios.

Chain reactions - branching chains, explosions, oscillating reactions.

Catalysis :

Homogeneous, surface (adsorption isotherms, precursor states, Langmuir-Hinshelwood and Eley-Rideal mechanisms).

Relaxation methods to study kinetics :

Pressure jump, temperature jump, reaction close to equilibrium.

Practical work :

Measurement of kinetic parameters experimentally and in IT simulations. Deduction of reaction mechanisms from kinetic data. Calculation of surface area from adsorption isotherms.