How to Calculate Solubility Product
What is Solubility Product?
Solubility product (K_sp) = [cation]ⁿ[anion]ᵐ at equilibrium; determines whether precipitate forms when ions mixed.
Step-by-Step Guide
- 1Input K_sp and ion concentrations
- 2Calculate Q (reaction quotient)
- 3Determine if precipitate forms (Q > K_sp)
Worked Examples
Input
AgCl: K_sp = 1.8×10⁻¹⁰, [Ag⁺] = [Cl⁻] = 10⁻⁵ M
Result
Q = 10⁻¹⁰ = K_sp (at equilibrium, no ppt)
Common Mistakes to Avoid
- ✕Confusing K_sp with solubility (different units)
- ✕Not accounting for common ion effect
Frequently Asked Questions
How do you calculate solubility from K_sp?
For AgX: s = √K_sp; for AgX₂: s = ∛(K_sp/4); depends on stoichiometry.
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