DP Chemistry (last assessment 2024)
Question 22M.2.hl.TZ1.5d(iv)
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.2.hl.TZ1.5d(iv) |
| Level | hl | Paper | 2 | Time zone | TZ1 |
| Command term | Justify, Outline | Question number | d(iv) | Adapted from | N/A |
d(iv).
[Maximum mark: 1]
22M.2.hl.TZ1.5d(iv)
Organomagnesium compounds can react with carbonyl compounds. One overall equation is:
Iodomethane is used to prepare CH3Mg. It can also be converted into methanol:
CH3 + HO– → CH3OH + –
(d(iv))
The polarity of the carbon–halogen bond, C–X, facilitates attack by HO–.
Outline, giving a reason, how the bond polarity changes going down group 17.
[1]
Markscheme
decreases/less polar AND electronegativity «of the halogen» decreases ✔
Accept “decreases” AND a correct comparison of the electronegativity of two halogens.
Accept “decreases” AND “attraction for valence electrons decreases”.
Examiners report
Good performance on how the polarity of C-X bond changes going down group 17.
