DP Chemistry (last assessment 2024)

Question 20N.2.hl.TZ0.2f(ii)

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.2.hl.TZ0.2f(ii)
Level	hl	Paper	2	Time zone	TZ0
Command term	Calculate	Question number	f(ii)	Adapted from	N/A

f(ii).

[Maximum mark: 1]

20N.2.hl.TZ0.2f(ii)

Compound A is in equilibrium with compound B.

(f(ii))

Calculate the standard Gibbs free energy change, $∆ G^{⦵}$ , in $kJ {mol}^{- 1}$ , for the reaction (A to B) at $298 K$ . Use sections 1 and 2 of the data booklet.

[1]

Markscheme

$« Δ G^{Θ} = - R T \ln K = 0.00831 kJ {mol}^{- 1} K^{- 1} (298 K) (\ln 1.0 \times 10^{8}) = »$
$- 46 « kJ {mol}^{- 1} »$ ✔

Examiners report

Most candidates could apply the formula for Gibbs free energy change, ΔG^Θ, correctly however some did not get the units correct.

Syllabus sections

Additional higher level (AHL)

Additional higher level (AHL) » Topic 15: Energetics/thermochemistry » 15.2 Entropy and spontaneity

Additional higher level (AHL) » Topic 15: Energetics/thermochemistry

Question 20N.2.hl.TZ0.2f(ii)

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