Quick answer: The solubility product Ksp is the equilibrium constant for a sparingly soluble ionic solid dissolving, such as AgCl(s) ⇌ Ag⁺ + Cl⁻, with Ksp = [Ag⁺][Cl⁻]. This AP Chemistry test on solubility product Ksp has 8 questions worth 20 marks, to do in 45 minutes: writing Ksp, molar solubility and ksp from mass solubility. The mark scheme is on a separate page; free printable PDF.
Answer all questions and show your working. A calculator is allowed. Give Ksp values to two significant figures. Use Ksp(AgCl) = 1.8 × 10⁻¹⁰ where it is not stated.
Level: AP Chemistry · Curriculum: AP Chem Unit 7
Question 1 Writing Ksp (2 marks)
Write the Ksp expression for Ca₃(PO₄)₂ and express it in terms of the molar solubility s. (2 marks)Question 2 Molar solubility (3 marks)
Ksp(PbF₂) = 3.3 × 10⁻⁸. Calculate the molar solubility and [F⁻] in a saturated solution. (3 marks)Question 3 Ksp from mass solubility (3 marks)
0.62 g of BaF₂ (M = 175.3 g/mol) dissolves in 1.00 dm³ of water. Calculate Ksp. (3 marks)Question 4 Common ion calculation (3 marks)
Calculate the molar solubility of AgCl in 0.020 mol/dm³ AgNO₃ (Ksp = 1.8 × 10⁻¹⁰) and explain why it is smaller than in pure water. (3 marks)Question 5 Precipitation test (3 marks)
40.0 cm³ of 1.0 × 10⁻³ mol/dm³ BaCl₂ is mixed with 60.0 cm³ of 2.0 × 10⁻⁴ mol/dm³ Na₂SO₄. Ksp(BaSO₄) = 1.1 × 10⁻¹⁰. Show by calculation whether a precipitate forms. (3 marks)Question 6 Solubility in acid (2 marks)
Explain why CaCO₃ dissolves in dilute hydrochloric acid but AgCl does not. (2 marks)Question 7 Saturated solution diagram (2 marks)
Question 8 Comparing salts (2 marks)
Ksp(AgCl) = 1.8 × 10⁻¹⁰ and Ksp(AgI) = 8.5 × 10⁻¹⁷. Both are 1:1 salts. Calculate how many times more soluble AgCl is than AgI. (2 marks)
