Solubility Product (Ksp) Calculator
Calculate Ksp from molar solubility, or find molar solubility from Ksp.
Supports ionic compounds with presets for AgCl, BaSO4, CaF2, and more.
Solubility
The solubility product constant (Ksp) describes the equilibrium between an ionic solid and its dissolved ions.
For the dissolution: MₓNy(s) ⇌ xM^(y+)(aq) + yN^(x-)(aq)
Ksp = [M^(y+)]^x × [N^(x-)]^y
From molar solubility (s mol/L):
[M^(y+)] = x × s
[N^(x-)] = y × s
Ksp = (xs)^x × (ys)^y
From Ksp to solubility (solving for s):
For 1:1 salt (MX): Ksp = s² → s = √Ksp
For 1:2 salt (MX₂): Ksp = (s)(2s)² = 4s³ → s = (Ksp/4)^(1/3)
For 1:3 salt (MX₃): Ksp = (s)(3s)³ = 27s⁴ → s = (Ksp/27)^(1/4)
Common Ksp values at 25°C:
| Compound | Formula | Ksp |
|---|---|---|
| Silver chloride | AgCl | 1.8 × 10⁻¹⁰ |
| Barium sulfate | BaSO₄ | 1.1 × 10⁻¹⁰ |
| Calcium fluoride | CaF₂ | 3.9 × 10⁻¹¹ |
| Lead iodide | PbI₂ | 9.8 × 10⁻⁹ |
| Calcium carbonate | CaCO₃ | 3.4 × 10⁻⁹ |
| Iron(II) hydroxide | Fe(OH)₂ | 4.9 × 10⁻¹⁷ |
| Aluminum hydroxide | Al(OH)₃ | 1.9 × 10⁻³³ |
Predicting precipitation: Compare the ion product (Q_sp) to Ksp:
- Q_sp > Ksp → precipitation occurs
- Q_sp < Ksp → solution is unsaturated (no precipitate)
- Q_sp = Ksp → saturated (at the edge of precipitation)