Question 20N.3.sl.TZ0.1c
| Date | November 2020 | Marks available | [Maximum mark: 1] | Reference code | 20N.3.sl.TZ0.1c |
| Level | sl | Paper | 3 | Time zone | TZ0 |
| Command term | Suggest | Question number | c | Adapted from | N/A |
In order to determine the oil content of different types of potato crisps (chips), a student weighed of crushed crisps and mixed them with of non-polar solvent.
She assumed all the oil in the crisps dissolved in the solvent.
The student then filtered the mixture to remove any solids, and gently heated the solution on a hot plate to evaporate the solvent.
She measured the mass of the oil that remained from each type of crisps
Non-polar solvents can be toxic. Suggest a modification to the experiment which allows the evaporated solvent to be collected.
[1]
distillation «instead of evaporation» ✔
Accept “pass vapour through a condenser and collect liquid”.
Do not accept “condensation” without experimental details.
A bit disappointing as the number of correct answers were substantially lower than expected. Many students responded using a fume hood or other method to remove the solvent. Once again this indicates a general misunderstanding about experimental methods.
