DP Chemistry (last assessment 2024)

Question 20N.2.hl.TZ0.b

Date	November 2020	Marks available	[Maximum mark: 2]	Reference code	20N.2.hl.TZ0.b
Level	hl	Paper	2	Time zone	TZ0
Command term	Calculate	Question number	b	Adapted from	N/A

[Maximum mark: 2]

20N.2.hl.TZ0.b

An equation for the combustion of propane is given below.

C₃H₈(g) + 5O₂(g) 3CO₂(g) + 4H₂O(g)

Calculate the standard enthalpy change, $∆ H^{⦵}$ , for this reaction using section 12 of the data booklet.

[2]

Markscheme

$4 (- 241.8 « kJ »)$ AND $3 (- 393.5 « kJ »)$ AND $« 1 » (- 105 « kJ »)$ ✔
$« Δ H^{⦵} = 4 (- 241.8 « kJ ») + 3 (- 393.5 « kJ ») - « 1 » (- 105 « kJ ») = » - 2043 « kJ »$ ✔

Award [2] for correct final answer.

Award [1 max] for $- 2219 « k J »$ .

Examiners report

Enthalpy calculations using enthalpy of formation data were generally well done.

Syllabus sections

Core

Core » Topic 5: Energetics/thermochemistry » 5.3 Bond enthalpies

Core » Topic 5: Energetics/thermochemistry

Question 20N.2.hl.TZ0.b

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