DP Chemistry (last assessment 2024)
Question 22M.1.sl.TZ2.30
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.1.sl.TZ2.30 |
| Level | sl | Paper | 1 | Time zone | TZ2 |
| Command term | Interpret | Question number | 30 | Adapted from | N/A |
30.
[Maximum mark: 1]
22M.1.sl.TZ2.30
20 cm3 of 1 mol dm−3 sulfuric acid was added dropwise to 20 cm3 of 1 mol dm−3 barium hydroxide producing a precipitate of barium sulfate.
H2SO4 (aq) + Ba(OH)2 (aq) → 2H2O (l) + BaSO4 (s)
Which graph represents a plot of conductivity against volume of acid added?
[1]
Markscheme
B
Examiners report
The question involved the formation of a precipitate – not a familiar concept to the candidates. It required candidates (to work out how the number of ions and hence conductivity were changing. 37% of the candidates got the correct answer (conductivity decreased as volume of H2SO4 increased). The majority increased conductivity as H2SO4 was added.