WEB TUTORIAL

Composite Reactions & the Steady State Approximation

Introduction

The following pages provide a self-study Tutorial on Composite Reactions and the Steady State Approximation (SSA), and are designed to be of assistance in deriving appropriate Rate Expressions for the two Mechanisms proposed in the Year 2 "Halogenation of Propanone" practical.

Contents of Tutorial

Chapter	Title	Contents	Pages
1	Basic Principles	Definitions · Reaction Rates · Order of Reaction · Rate Constants · 0th, 1st and 2nd Order Kinetics	7
2	Composite Reactions and the SSA	Types of Composite Reactions · General Strategy for dealing with Composite Reactions · The SSA	4
3	Decomposition of Azomethane	Worked Example (including intermediate steps)	16
4	Halogenation of Propanone	Worked Example (excluding intermediate steps)	11

General Notes

Questions (or statements) in green will appear throughout these pages, followed by a set of multiple-choice answers in blue. To progress, the correct answer needs to be selected. If an incorrect answer is chosen, hints/help will be displayed and the question asked again.

It is recommended that (relevant) notes are taken down whilst studing the tutorial. The tutorial will also be of more use if an attempt is made to answer the questions, before looking at the list of multiple choice answers.

If there are any problems, either with this Tutorial or with the write-up for the "Halogenation of Propanone" practical, please contact Col Flowers.

A Note on Browsers and the Extended Character Set

Some Browsers do not support the Extended Character Set used in this Tutorial. This results in certain symbols being erroneously displayed. To check whether the Browser being used supports the Extended Character Set, look at the symbols displayed in the boxes below.

α

β

References

• P.Atkins, Physical Chemistry, Oxford, 1988.
• G.Denuault and A.Russell, CH213 - The Pace of Change (Lecture Notes), unpublished, 1999.
• C.Flowers, Year 2 - Halogenation of Propanone (Laboratory Script), unpublished, 2000.
• H.Folger, Elements of Chemical Reaction Engineering, Prentice Hall, 1992.
• M.Pilling and P.Seakins, Reaction Kinetics, Oxford, 1999.