IB Chemistry HL R2.3 How far? The extent of chemical change questions

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Question 1

Paper 2Easy5 marks

A student prepares an aqueous solution of ethanoic acid at 298 K298\ \mathrm{K} The dissociation equilibrium is

\ceCH3COOH(aq)+H2O(l)<=>H3O+(aq)+CH3COO−(aq)\ce{CH3COOH(aq) + H2O(l) <=> H3O+(aq) + CH3COO-(aq)}

At 298 K298\ \mathrm{K} Ka=1.80×10−5K_\mathrm{a}=1.80\times10^{-5} Figure 1 shows the initial concentration of ethanoic acid.

CH3COOH(aq)initial concentration =0.100 mol dm−3
(a)

Using Figure 1, calculate the equilibrium concentration of \ceH3O+\ce{H3O+} Assume that [\ceCH3COOH]equilibrium≈[\ceCH3COOH]initial[\ce{CH3COOH}]_\mathrm{equilibrium}\approx[\ce{CH3COOH}]_\mathrm{initial} Give your answer to three significant figures.

[2]
(b)

Use the equation in the data booklet to calculate ΔG∘\Delta G^\circ in kJ mol−1\mathrm{kJ\,mol^{-1}} for the dissociation equilibrium at 298 K298\ \mathrm{K}

[2]
(c)

State which side of the equilibrium is favoured.

[1]

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