IB Chemistry SL Reactivity 2.3.3 Equilibrium Constant K

Practise interpreting the magnitude of K as the extent of reaction at a specified temperature. Values much greater than one favour products, values much less than one favour…

Syllabus
First assessment 2025
Objective
2.3.3
Level
SL

Exam points

  • interpret K magnitude as product- or reactant-favoured equilibrium rather than reaction rate
  • use Kreverse = 1/Kforward and apply powers when an equation is multiplied
  • state that only a temperature change alters K for the same fixed balanced reaction

2.3.3—Equilibrium constant (K) question 1

[Maximum number: 1]

The reaction between ethanoic acid and ethanol is homogeneous and reversible.

C2H6O(l)+C2H4O2(l)⇌C4H8O2(l)+H2O(l)ΔHθr=−4 kJ mol−1\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}(\mathrm{l})+\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}_{2}(\mathrm{l}) \rightleftharpoons \mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}(\mathrm{l})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \quad \Delta H^{\theta}{ }_{\mathrm{r}}=-4 \mathrm{~kJ} \mathrm{~mol}^{-1}

Explain the effect of reducing the temperature on the value of the equilibrium constant.

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