Analysis of 2012 Cambridge Singapore A level Chem Paper 3
2012 Cambridge-Singapore Chem Papers are difficult, surprising but still doeable. Paper 3 1(a) Candidates need to illustrate the reaction of aluminium oxide with aqueous sodium hydroxide to form a complex. Candidates need to link the partial covalent character in the ionic bonds of aluminium oxide to the amphoteric character of aluminium oxide. (b)(i) Candidates need to learn what are dative bonds in chemical bonding. (b)(iv) Students need to be careful to convert cm3 to m3, which is the SI unit. Cambridge examiners seem to favor the chapter of chemical equilibrium in recent years. (c) I mentioned Friedal Craft acylation and alkylation in my post last year (Tips for 2012 JC2 students) , and it came out in exams. Compound B is formed by the electrophilic attack of the acyl group (now as a carbocation) on the benzene ring. This is an intra-molecular reaction wh...