chemical kinetics and mechanism

[...]... define the rate of reaction and so (3.6) It is common practice in chemical kinetics (as well as in chemical thermodynamics) to use a chemical reaction written in an 'alphabetical' form to help to express a definition in a general way Thus, we could write a chemical reaction with known stoichiometry as U A + hB + = pP + qQ + (3.7) where A, B and so on, represent reactants and P, Q and so on, represent products... the reactants (before a reaction begins) and the final state of the system when an equilibrium is reached (so that there is no longer any net change) What happens between these initial and final states of reaction and exactly how, and how quickly, the transition from one to the other occurs is the province of chemical kinetics At the molecular level chemical kinetics seeks to describe the behaviour... single bromoethane molecule encounters, and reacts with, a single hydroxide ion in solution As these species come closer and closer together they interact and, as a consequence, chemical bonds become distorted and the overall potential energy increases At distances typical of chemical bond lengths, the reactant species become partially bonded together and new chemical bonds begin to form At this point... intermediate species, and which passes through a single transition state A chemical reaction that proceeds by a series of elementary steps is known as a composite reaction and the corresponding mechanism is referred to as a composite reaction mechanism, or just composite mechanism All reaction mechanisms with more than one step will involve intermediate species These are formed in one step and consumed, in... life, we refer to a rate of change in position as speed and measure it as the distance travelled in a given time (Figure 1.1) The study of movement in general is the subject of kinetics and chemical kinetics, in particular, is concerned with the measurement and interpretation of the rates of chemical reactions It is an area quite distinct from that of chemical thermodynamics which is concerned only with... called the kinetic theory of chemical actions, the theory namely, that the direction and amount of any chemical change is conditioned not only by the affinities, but also by the masses of reacting substances, by the temperature, pressure, and other physical circumstances - is being gradually accepted, and illustrated by experimental results.’ Over a century later, chemical kinetics remains a field of... substances combine with one another and in developing a system of shorthand notation for representing chemical reactions As a result, when we now think of the interaction of hydrogen and oxygen, for example, we tend to think automatically in terms of a balanced chemical equation This equation serves to identify the species taking part and shows that for every two H2 molecules and one 0 2 molecule that react,... reaction The corresponding mechanism, Reactions 2.5 and 2.6, is referred to as a composite reaction mechanism, or just a composite mechanism In general, for any composite reaction, the number and nature of the steps in the mechanism cannot be deduced from the stoichiometry This point is emphasized when we consider that the apparently simple reaction between hydrogen gas and oxygen gas to give water... known to describe the rates of a wide range of different chemical processes Indeed, such relationships lie at the heart of Figure 1.1 The tennis ball may well leave the racket at a speed greater than 55 metres per second 12 empirical chemical kinetics, that is an approach to chemical kinetics in which the aim is to describe the progress of a chemical reaction with time in the simplest possible mathematical... the Kinetics Toolkit The Kinetics Toolkit is provided so that you can focus your attention on the underlying principles of the analysis of chemical kinetic data rather than becoming involved in the time-consuming process of manipulating data sets and graph plotting Full sets of data are provided for most of the examples that are used in the main text and you should, as a matter of course, use the Kinetics . Chemical Kinetics and Mechanism