| Date | May 2009 | Marks available | 3 | Reference code | 09M.3.sl.TZ2.F3 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Explain | Question number | F3 | Adapted from | N/A |
Question
Explain why raw meat changes colour from purplish-red to brown on standing.
Markscheme
purplish-red colour of meat is produced by myoglobin;
Accept heme.
Fe has oxidation state +2 in myoglobin;
(upon standing) oxidizes to \({\text{F}}{{\text{e}}^{3 + }}\) which is brown;
Examiners report
Many candidates had difficulties explaining the brown colouring of meat upon standing.
