SAJC 2026 Solubility Equilibria Assignment (Student)

1 St Andrew’s Junior College H2 Chemistry 2025 Assignment 20: Solubility Equilibria 1. [2008/P2/Q2] Silver forms a series of halides of general formula Ag X. The chloride, bromide and iodide of silver are sparingly soluble in water at room temperature. Data about the solubilities in water and the solubility products of the chloride, bromide and iodide of silver at 298 K are given below. Salt Solubility / mol dm–3 Solubility product / mol2 dm–6 AgCl 1.4 × 10–5 2.0 × 10–10 AgBr 7.1 × 10–7 to be calculated AgI 8.9 × 10–9 8.0 × 10–17 In this question, give each of your numerical answers to one decimal place. (a) (i) Write an expression for the solubility product, Ksp,of silver bromide. [1] (ii) From the data above, calculate a value for Ksp of silver bromide. [1] (b) When a precipitate is formed, Δ Goppt, in J mol –1, is given by the following expression. ΔGoppt = 2.303RT lg Ksp Use the data above to calculate ΔGoppt, in kJ mol–1, for silver chloride. [1]

2 2. [2017/P3/Q1e] modified Silver chloride is sparingly soluble in water. AgCl (s) Ag+ (aq) + Cl– (aq) (i) Write the expression for the solubility product, Ksp, of silver chloride, stating its units. [2] (ii) An excess of solid silver chloride was stirred with 0.50 mol dm−3 AgNO3 until equilibrium was established. Calculate [Cl−(aq)] in the resulting solution, given the value of Ksp is 2.0 x 10−10. [1] (iii) Describe and explain how the solubility of AgCl is affected by • adding NH3 (aq), • adding NaCl (aq). [3]

3 3. [2016/P1/Q13] modified What is [Ba2+] in the solution when BaF2 just precipitates? [2]

4 4. A solution contains 1.5 x 10 –2 mol dm–3 I– and 8.0 x 10 –3 mol dm–3 C2O42–. If aqueous Pb(NO3)2 is added, predict which of the following solid, PbI2 or PbC2O4 will be precipitated out first. [2] Ksp of PbI2 = 9.8 x 10–9 mol3 dm–9 and Ksp of PbC2O4 = 8.5 x 10–9 mol2 dm–6 at 298K.