DP Chemistry (last assessment 2024)
Question 21M.2.sl.TZ2.4b
| Date | May 2021 | Marks available | [Maximum mark: 3] | Reference code | 21M.2.sl.TZ2.4b |
| Level | sl | Paper | 2 | Time zone | TZ2 |
| Command term | Determine | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 3]
21M.2.sl.TZ2.4b
Organic chemistry can be used to synthesize a variety of products.
(b)
Determine the change in enthalpy, ΔH, for the combustion of but-2-ene, using section 11 of the data booklet.
CH3CH=CHCH3 (g) + 6O2 (g) → 4CO2 (g) + 4H2O (g)
[3]
Markscheme
Bonds broken:
2(C–C) + 1(C=C) + 8(C–H) + 6O=O / 2(346) + 1(614) + 8(414) + 6(498) / 7606 «kJ» ✓
Bonds formed:
8(C=O) + 8(O–H) / 8(804) + 8(463) / 10 136 «kJ» ✓
Enthalpy change:
«Bonds broken – Bonds formed = 7606 kJ – 10 136 kJ =» –2530 «kJ» ✓
Award [2 max] for «+» 2530 «kJ».
Award [3] for correct final answer.
