Question 20N.3.hl.TZ0.c(i)
| Date | November 2020 | Marks available | [Maximum mark: 2] | Reference code | 20N.3.hl.TZ0.c(i) |
| Level | hl | Paper | 3 | Time zone | TZ0 |
| Command term | State and explain | Question number | c(i) | Adapted from | N/A |
Consider the structures of medicinal molecules in section 37 of the data booklet.
State and explain the relative solubility of codeine in water compared to morphine and diamorphine.
[2]
codeine less soluble «in water» than morphine AND more soluble than diamorphine
OR
morphine > codeine > diamorphine «in terms of solubility in water» ✔
more/stronger/greater hydrogen/H bonding «due to more hydroxyl groups leads to greater solubility» ✔
Only the better candidates were able to state and explain the relative solubility of codeine in water compared to morphine and diamorphine. The majority scored M1 for the correct order of relative solubility. Few gave a comprehensive explanation outlining that there is greater hydrogen bonding due to more hydroxyl groups, which results in greater solubility.
