Chapter 4
Study tips and resources for Chapter 4 – Physical Chemistry by Laidler, Meiser, Sanctuary
This clip from the Physical Chemistry book explains how concentration changes with pressure. Changing the pressure on a gas can change the number of moles.
This leads us to the concept of the chemical potential: each compound has a potential to react and has its own molar Gibbs free energy. The greater the chemical potential is negative (at constant T and P) the greater the potential to react and minimize the Gibbs energy for the whole reaction.
In class, I used the animation in chapter 4- Approach equilibrium (page 4.28 of my Physical Chemistry book), to show that the ratio of the forward and reverse rate constants is equal to the equilibrium constant. Continue reading
Chemistry would be a whole lot simpler if all the reactions would just make their expected products (or even some by-products) and then be done. Reactants and products have a mind of their own though and are influenced by temperature, concentration, some even by the weather (pressure)! Worse, some products can’t seem to make up their mind and turn back into reactants. Continue reading
When dealing with chemical reactants, three important questions are usually asked.
(1) What product(s) can be made,
(2) How much can be made and
(3) How fast can it be made. Continue reading

Screen grab showing equilibrium using interactive animation (with audo explanation) from chapter 4 (click to enlarge)
Equilibrium is certainly one of the most interesting topics for a chemist! However, it seems that to study it is neither easy (nor enjoyable) for our students. This is probably due to the inherent difficulty in handling a system not using a state function corresponding to an observable; using rather, this strange equilibrium constant, a “practical” interpretation of which may seem unclear. Continue reading