IB Chemistry HL 1.4.4 Equilibrium and Gibbs energy Question Bank

Practise IB Chemistry HL 1.4.4 by applying equilibrium and gibbs energy to exam-style questions.

Exam points

identify the relevant chemical structure, process or evidence
apply the correct chemical model or equation
evaluate the result using chemical reasoning and data

[Maximum number: 2]

Sulfur trioxide is an important compound in industry.

$\quad \mathrm{SO}_{3}(\mathrm{~g})$ is made using the contact process.

2 \mathrm{SO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{SO}_{3}(\mathrm{~g}) \quad \Delta H^{\ominus}<0

Calculate the value of the equilibrium constant for the formation of $\mathrm{SO}_{3}(\mathrm{~g})$ at 773 K . Use sections 1 and 2 of the data booklet. If you did not obtain an answer to (d)(viii), use $-25.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$ , although this is not the correct answer.

$\begin{aligned} <-25.8 \times 10^{3}=-8.31 \times 773 \times \ln K> \ln K=<\frac{-25.8 \times 10^{3}}{-8.31 \times 773}=-4.016 K=55.5 \end{aligned}$

Award [2] for correct final answer.

Accept answers in the range 55-60.

Award [2] for K=49.0 if $-25.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$ was used.

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1.4.4 (HL)—Equilibrium and Gibbs energy question 1