Solubility product: Class 11 practice
For a salt AₓBᵧ with solubility s mol/L, Ksp = (xs)ˣ(ys)ʸ. Read the method, follow the three worked examples, then try the six questions.
What you should know first
- Powers and roots
The idea behind solubility product
For a salt AₓBᵧ with solubility s mol/L, Ksp = (xs)ˣ(ys)ʸ. For AB, Ksp = s²; for AB₂, Ksp = 4s³. A precipitate forms when the ionic product exceeds Ksp.
Step-by-step method
- Write the dissolution equation.
- Express ion concentrations in terms of s.
- Ksp = product with powers; solve for s or Ksp.
Worked example 1 (Basic)
The solubility of AgCl is 5e-4 mol/L. Find its Ksp.
- Ksp = s²
- = 2.50e-7
- Answer: 2.50e-7
Worked example 2 (Standard)
The solubility of CaF₂ is 1e-3 mol/L. Find its Ksp.
- [Ca²⁺] = s, [F⁻] = 2s
- Ksp = 4s³ = 4.00e-9
- Answer: 4.00e-9
Worked example 3 (Challenge)
Ksp of a salt AB is 9e-10. Find its solubility.
- s = √Ksp
- = 3.000e-5 mol/L
- Answer: 3.000e-5 mol/L
Common mistakes and misconceptions
- Forgetting the coefficient (2s)²
- Using s instead of s² for AB salts
Practice questions
- (Basic) The solubility of AgCl is 7e-5 mol/L. Find its Ksp.
- (Basic) The solubility of AgCl is 3e-5 mol/L. Find its Ksp.
- (Standard) The solubility of CaF₂ is 1e-4 mol/L. Find its Ksp.
- (Standard) The solubility of CaF₂ is 3e-5 mol/L. Find its Ksp.
- (Challenge) Ksp of a salt AB is 4e-11. Find its solubility.
- (Challenge) Ksp of a salt AB is 2e-10. Find its solubility.
Answer key with full working
- Q1: Ksp = s² → = 4.90e-9 → Answer: 4.90e-9
- Q2: Ksp = s² → = 9.00e-10 → Answer: 9.00e-10
- Q3: [Ca²⁺] = s, [F⁻] = 2s → Ksp = 4s³ = 4.00e-12 → Answer: 4.00e-12
- Q4: [Ca²⁺] = s, [F⁻] = 2s → Ksp = 4s³ = 1.08e-13 → Answer: 1.08e-13
- Q5: s = √Ksp → = 6.325e-6 mol/L → Answer: 6.325e-6 mol/L
- Q6: s = √Ksp → = 1.414e-5 mol/L → Answer: 1.414e-5 mol/L
Syllabus note
This skill is listed under "Equilibrium" for Class 11 in the NCERT/CBSE books. ICSE, IGCSE, IB and state boards may teach it in a different chapter or year.
Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.
Related practice and notes
Frequently asked questions
Which chapter is solubility product in?
"Equilibrium", Class 11 Chemistry (NCERT/CBSE). Other boards may place it differently.
How were the answers checked?
Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.