Question 19M.3.hl.TZ1.a
| Date | May 2019 | Marks available | [Maximum mark: 3] | Reference code | 19M.3.hl.TZ1.a |
| Level | hl | Paper | 3 | Time zone | TZ1 |
| Command term | Explain | Question number | a | Adapted from | N/A |
The main fatty acid composition of cocoa butter and coconut oil is detailed below.
The melting points of cocoa butter and coconut oil are 34 °C and 25 °C respectively.
Explain this in terms of their saturated fatty acid composition.
[3]
coconut oil has higher content of lauric/short-chain «saturated» fatty acids
OR
cocoa butter has higher content of stearic/palmitic/longer chain «saturated» fatty acids [✔]
longer chain fatty acids have greater surface area/larger electron cloud [✔]
stronger London/dispersion/instantaneous dipole-induced dipole forces «between triglycerides of longer chain saturated fatty acids» [✔]
Note: Do not accept arguments that relate to melting points of saturated and unsaturated fats.
Candidates had difficulty explaining the melting points of fats in terms of length of carbon chain, and referred instead to an explanation of saturated and unsaturated fat structures.
