Ksp Calculator – Solubility Product Constant Made Simple

Calculate the solubility product constant (Ksp) or find ion concentrations at equilibrium with our Ksp calculator. Essential for understanding sparingly soluble salts and equilibrium chemistry. Perfect for general and analytical chemistry.

Calculate

Cation Concentration [Mⁿ⁺] (mol/L)

Anion Concentration [Xᵐ⁻] (mol/L)

Cation Coefficient (m)

Anion Coefficient (n)

Understanding Solubility Product (Ksp)

Ksp is the equilibrium constant for a solid dissolving in water. It represents the product of ion concentrations at equilibrium, each raised to the power of its coefficient. Lower Ksp values indicate less soluble compounds.

Ksp Expression

For a salt MₘXₙ dissociating: MₘXₙ(s) ⇌ m Mⁿ⁺(aq) + n Xᵐ⁻(aq)

Ksp = [Mⁿ⁺]ᵐ × [Xᵐ⁻]ⁿ

Molar Solubility

Molar solubility (s) is the number of moles of salt that dissolve per liter. For MₘXₙ:

[Mⁿ⁺] = m × s

[Xᵐ⁻] = n × s

Ksp = (m×s)ᵐ × (n×s)ⁿ = mᵐ × nⁿ × sᵐ⁺ⁿ

s = (Ksp / (mᵐ × nⁿ))^(1/(m+n))

Common Ksp Values (25°C)

Compound	Formula	Ksp	Solubility
Silver chloride	AgCl	1.8 × 10⁻¹⁰	1.3 × 10⁻⁵ M
Barium sulfate	BaSO₄	1.1 × 10⁻¹⁰	1.0 × 10⁻⁵ M
Calcium carbonate	CaCO₃	3.4 × 10⁻⁹	5.8 × 10⁻⁵ M
Lead(II) iodide	PbI₂	7.1 × 10⁻⁹	1.2 × 10⁻³ M
Calcium fluoride	CaF₂	3.5 × 10⁻¹¹	2.1 × 10⁻⁴ M

Example: AgCl

AgCl(s) ⇌ Ag⁺(aq) + Cl⁻(aq)

Ksp = [Ag⁺][Cl⁻] = 1.8 × 10⁻¹⁰

If [Ag⁺] = [Cl⁻] = s, then s² = 1.8 × 10⁻¹⁰, s = 1.3 × 10⁻⁵ M

Ion Concentration Comparison

Enter values and calculate to see the chart

Ksp Applications

Predicting precipitation in chemical reactions
Water treatment and hardness removal
Qualitative analysis of metal ions
Understanding kidney stone formation
Pharmaceutical formulation stability
Geochemical mineral dissolution

How the Ksp Calculator Works

Choose Calculation Mode

Select whether to find Ksp from concentrations or solubility from Ksp.

Enter Values

Input ion concentrations or Ksp value along with stoichiometric coefficients.

Get Results

View Ksp, molar solubility, and ion concentrations with visual comparison.

Frequently Asked Questions

What does Ksp tell us about solubility?

Ksp indicates how much of a compound can dissolve in water. Lower Ksp values mean less soluble compounds. However, Ksp values can only be directly compared for compounds with the same ion ratio.

How do you calculate molar solubility from Ksp?

For a salt MₘXₙ, molar solubility s = (Ksp / (m^m × n^n))^(1/(m+n)). For simple 1:1 salts like AgCl, s = √Ksp.

What factors affect Ksp?

Ksp is temperature-dependent but independent of concentration. Increasing temperature generally increases Ksp for endothermic dissolution processes.

When does precipitation occur?

Precipitation occurs when the ion product (Q) exceeds Ksp. If Q < Ksp, the solution is unsaturated. If Q = Ksp, the solution is at equilibrium.

What is the common ion effect?

Adding a common ion (an ion already present in the equilibrium) decreases solubility by shifting equilibrium toward the solid, according to Le Chatelier's principle.

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