DP Chemistry (first assessment 2025)

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Question 21M.2.HL.TZ2.7c

Date	May 2021	Marks available	[Maximum mark: 2]	Reference code	21M.2.HL.TZ2.7c
Level	HL	Paper	2	Time zone	TZ2
Command term	Determine	Question number	c	Adapted from	N/A

c.

[Maximum mark: 2]

21M.2.HL.TZ2.7c

(c)

SO₂ (g), O₂(g) and SO₃(g) are mixed and allowed to reach equilibrium at 600 °C.

Determine the value of K_c at 600 °C.

[2]

Markscheme

[O₂] = 1.25 «mol dm⁻³» AND [SO₃] = 3.50 «mol dm⁻³» ✓

«K_c = $\frac{{[3.50]}^{2}}{{[1.50]}^{2} [1.25]}$ =» 4.36 ✓

Award [2] for correct final answer

Syllabus sections

Reactivity 2. How much, how fast and how far? » Reactivity 2.3—How far? The extent of chemical change » Reactivity 2.3.6—The equilibrium law is the basis for quantifying the composition of an equilibrium mixture. Solve problems involving values of K and initial and equilibrium concentrations of the components of an equilibrium mixture.