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CAIE A-Level Chemistry 7.1.1 Reversible Reactions and Dynamic Equilibrium

Practise explaining reversible reactions and dynamic equilibrium through equal opposing rates in a closed system.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • state that a reversible reaction can proceed in both forward and reverse directions
  • define dynamic equilibrium by equal forward and reverse rates, not by reactions having stopped
  • identify a closed system as necessary and state that reactant and product concentrations remain constant

7.1.1—What is meant by a reversible reaction question 1

[Maximum number: 1]

The elements sodium to chlorine, in the third period, all form oxides.

SO3\mathrm{SO}_{3} is produced by the reaction between SO2\mathrm{SO}_{2} and O2\mathrm{O}_{2} in the Contact process. A dynamic equilibrium is established.

2SO2( g)+O2( g)⇌2SO3( g)ΔH=−196 kJ mol−12 \mathrm{SO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{SO}_{3}(\mathrm{~g}) \quad \Delta H=-196 \mathrm{~kJ} \mathrm{~mol}^{-1}

Explain why all three lines become horizontal.

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