DP Chemistry (last assessment 2024)

Question 20N.1.sl.TZ0.15

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.1.sl.TZ0.15
Level	sl	Paper	1	Time zone	TZ0
Command term	Derive	Question number	15	Adapted from	N/A

15.

[Maximum mark: 1]

20N.1.sl.TZ0.15

What is the $H - H$ bond enthalpy, in $kJ {mol}^{- 1}$ , in the $H_{2}$ molecule?

$2 H_{2} (g) + O_{2} (g) \to 2 H_{2} O (g)$

$∆ H_{f} (H_{2} O) = x kJ {mol}^{- 1}$

A. $x - y + 4 z$

B. $\frac{1}{2} (x - y + 4 z)$

C. $x - y + 2 z$

D. $\frac{1}{2} (x - y + 2 z)$

[1]

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Examiners report

There was no correct answer to this question as the value $∆ H_{f}$ was given instead of $∆ H_{r}$ . The majority of candidates answered as if it was $∆ H_{r}$

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Core

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

Core » Topic 5: Energetics/thermochemistry

Question 20N.1.sl.TZ0.15

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