Equilibria

The study of equilibria at A level can be divided into qualitative aspects, including the application of Le Chatelier's Pprinciple to deducing the effect of constraints on equilibrium yield and equilibrium position, and quantitaive treatments involving the equilibruium constant. Traditionally this has been reflected in the division of study between first and second year A level.

Qualitative aspects of the topic go little further than GCSE, and no new material beyond GCSE is added, although students are expected to have a deeper appreciation of the idea of compromise conditions in industrial manufacture.

The quantitative treatment includes developing an understanding of the equilibrium law and constant (Kc). Students often find it difficult to rationalise Le Chatelier's principle, and the effect of factors on equilibrium position and yield, with the fact that the only factor that affects the equilibrium constant is temperature. To many students this seems counter-intuitive.

Once the basic ideas of equilibrium are mastered the concept is applied to the much larger topic of acid-base equilibria, including calculation of pH for strong and weak acids and buffers. This area has been assigned to a separate list which also covers equilibria of gaseous sytems and Kp.

The 2015 revision of the A level syllabus has seen Kc moved to the first year of academic study and this is a departure from the previous revision.

As such this list provides resources relating to the first year of A level (or AS) which includes qualitative aspects and the equilibrium constant (Kc).

Second year topics may be found under the list Acid-Base Equilibria which also covers Kp.

Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or other recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.’