DP Chemistry (last assessment 2024)
Question 19M.2.sl.TZ2.c(iv)
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.2.sl.TZ2.c(iv) |
| Level | sl | Paper | 2 | Time zone | TZ2 |
| Command term | Predict | Question number | c(iv) | Adapted from | N/A |
c(iv).
[Maximum mark: 1]
19M.2.sl.TZ2.c(iv)
Ethyne, C2H2, reacts with oxygen in welding torches.
Ethyne reacts with steam.
C2H2 (g) + H2O (g) → C2H4O (g)
Two possible products are:
The enthalpy change for the reaction to produce B is −213 kJ. Predict, giving a reason, which product is the most stable.
[1]
Markscheme
B AND it has a more negative/lower enthalpy/«potential» energy
OR
B AND more exothermic «enthalpy of reaction from same starting point» [✔]
Examiners report
Reasonably well answered. About half of the candidates showed understanding of the relation between stability and the enthalpy change from the same starting materials. ECF was applied in this question based on the answer in part (iii).
