IB Chemistry SL Reactivity 2.3.2 Equilibrium Law

Practise deriving a homogeneous equilibrium-constant expression from the balanced equation. Raise each concentration to its stoichiometric coefficient, exclude no species unless…

Exam points

write product concentration terms over reactant terms from the balanced equation
use every stoichiometric coefficient as the exponent of its concentration term
calculate missing equilibrium amounts and divide by volume before evaluating K

[Maximum number: 1]

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

\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}

Deduce the expression for the equilibrium constant, K, for this reaction.

$\langle\mathrm{K}=\rangle \frac{\left[\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\right]\left[\mathrm{H}_{2} \mathrm{O}\right]}{\left[\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}\right]\left[\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}_{2}\right]}$

Marking guidance:

Do not accept expression without
$\mathrm{H}_{2} \mathrm{O}$ .

All question bank results loaded

2.3.2—Equilibrium law question 1