Define oxidation in terms of electron transfer.

Calculate the change in oxidation numbers of carbon and manganese.

Carbon:

Manganese:

Identify the oxidizing and reducing agents.

Oxidizing agent:

Reducing agent:

loss of electrons;

Carbon:

III to IV / +3 to +4 / (+)1;

Manganese:

VII to II / +7 to +2 / –5;

Penalize incorrect notation such as 3+ once only.

Oxidizing agent: \({\text{MnO}}_{\text{4}}^ - \) and Reducing agent: \({{\text{(COOH)}}_{\text{2}}}\);

Accept correct names instead of formulas.

Do not accept Mn and C.

Oxidation was generally correctly defined.

Many candidates calculated correctly the change in oxidation numbers, though often 2+ instead of +2 (or II) was given for the oxidation state of \({\text{M}}{{\text{n}}^{2 + }}\).

Marks were lost because candidates did not name the species but the elements or gave incorrect formula of \({{\text{(COOH)}}_{\text{2}}}\) or forgot the sign on \({\text{MnO}}_{\text{4}}^ - \).