Which conditions are required to obtain a good yield of a carboxylic acid when ethanol is oxidized using potassium dichromate(VI), \({{\text{K}}_{\text{2}}}{\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{7}}}{\text{(aq)}}\)?

I.     Add sulfuric acid

II.     Heat the reaction mixture under reflux

III.     Distil the product as the oxidizing agent is added

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

A

One teacher commented on the G2 form that this question required more specific knowledge than was indicated by the syllabus and indeed many candidates found this question challenging, as indicated by the very high number of blank responses and the difficulty index of 33%. The discrimination index of 0.23 showed that it was accessible to many of the better candidates.