In last year's exam, quite a few students gave the correct reactions, but were unable to clearly explain why the products were different in the two situations. As I have said many times before - don't make it hard for the markers, even though they are instructed to be as tolerant as they reasonably can be. Questions relating to this area of study frequently call for verbal responses and the drawing of molecular structures. Question 1 required students to identify the nature of some amino acids in water at various pH values. Question 3 was what has become a quite familiar style of question requiring a good deal of equation writing.
Students still seem to find it hard to get the equations right.
Of more interest, however, were parts b and c where students were required to sketch the hydrated copper ion and then describe the nature of the bonding within the water molecule and between the water molecule and the copper ion. This last point refers to the need to properly describe the ion-dipole bonding between the water molecules and the central ion. Peter McTigue is an associate professor and reader in chemistry and is currently director of the multimedia education unit at the University of Melbourne. He is chair of the CAT-setting panel for VCE chemistry.