Remember

Alcohols can be oxidised to aldehydes and aldehydes can be oxidised to acids (oxidising agent - sodium dichromate in sulphuric acid). The colour change observed during these oxidation reactions is orange (Cr+6) to green (Cr+3). Oxidation ofa primary alcohol yields an aldehyde, Oxidation ofa secondary alcohol yields a ketone. Aldehydes are easily oxidised whereas ketones are not easily oxidised.

Preparation of an aldehyde - excess alcohol is used.

Preparation of an acid - excess oxidising agent is used.