DP Chemistry (last assessment 2024)
Question 19M.3.hl.TZ1.b
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.hl.TZ1.b |
| Level | hl | Paper | 3 | Time zone | TZ1 |
| Command term | Outline | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 2]
19M.3.hl.TZ1.b
Methadone is a synthetic opiate administered as a racemic mixture to treat strong pain and morphine or heroin dependence.
Enantiomers can be identified using a polarimeter. Outline how this instrument differentiates the enantiomers.
[2]
Markscheme
«plane-»polarized light passed through sample [✔]
analyser/second polarizer determines angle of rotation of plane of plane-polarized light
OR
each enantiomer rotates plane «of plane-polarized light» in opposite directions «by the same angle» [✔]
Examiners report
Very poorly answered. Few scored any marks at all when outlining how a polarimeter can be used to differentiate between enantiomers. Many referred to the light or the enantiomers themselves being rotated.
