Energetics and Equilibria

These lectures are concerned with a very important topic in chemistry (and, more generally, in any molecular science): what makes a reaction ‘go’ and what determines to position of equilibrium. Put another way, we will be looking into what is the driving force for chemical reactions in order to explain why some reactions go entirely to products, whereas some come to a position of equilibrium in which there are significant amounts of reactants still present. We shall see there there is one very important physical law, the Second Law of Thermodynamics, which determines whether a reaction (or physical process) will ‘go’ and what the position of equilibrium is. The Law itself is simple to state, but working from this statement to practical relationships and ideas which we can apply is a fairly involved task. A substantial part of these lectures will be devoted to showing how the Second Law can be developed in this way; we will then go on to look at some applications.