Ksp Solubility Product Calculator

The Ksp Solubility Product Calculator converts between a salt's solubility product constant (Ksp) and its molar solubility — two key values in chemistry that describe how much of a sparingly soluble salt dissolves in water. Select your calculation mode, enter the cation and anion coefficients for your salt's formula (AxBy), and provide either a Ksp value or molar solubility to get the other. Optional common ion concentrations let you account for the common-ion effect, with secondary outputs including equilibrium ion concentrations and solubility in g/L.

What to Calculate *

Number of cations in the formula AxBy

Number of anions in the formula AxBy

Solubility product constant (use scientific notation)

Molar solubility in mol/L

Initial concentration of common cation (optional)

Initial concentration of common anion (optional)

Results

Primary Result

--

Equilibrium Cation Concentration

--

Equilibrium Anion Concentration

--

Solubility (g/L)

--

More Chemistry Tools

Frequently Asked Questions

What is a Ksp calculator and how does it work?

A Ksp calculator computes the solubility product constant or molar solubility for sparingly soluble ionic compounds. It uses the equilibrium expression Ksp = [A]^x[B]^y for a salt AxBy to determine how much of the compound dissolves in water at equilibrium.

How do I handle stoichiometric coefficients in Ksp calculations?

Enter the coefficients from your balanced dissolution equation. For example, CaF₂ → Ca²⁺ + 2F⁻ has x=1 (cation coefficient) and y=2 (anion coefficient). These coefficients are crucial for the correct Ksp expression.

What are common ions and how do they affect solubility?

Common ions are ions already present in solution before the salt dissolves. They reduce the solubility of the salt due to Le Chatelier's principle. Enter their initial concentrations in the common ion fields to account for this effect.

What units should I use for Ksp and solubility values?

Use mol/L for molar solubility and concentrations. Ksp values are typically very small numbers (like 1.8×10⁻¹⁰) and are unitless, though technically they have units of (mol/L)^(sum of coefficients).

How accurate are Ksp calculations and what factors affect them?

Ksp calculations assume ideal behavior and that activities equal concentrations. Real solutions may deviate due to ionic strength, temperature effects, and complex ion formation. Results are most accurate for dilute solutions at 25°C.

Can this calculator predict if precipitation will occur?

While this calculator focuses on equilibrium calculations, you can compare calculated ion concentrations with known Ksp values to predict precipitation. If the ion product Q exceeds Ksp, precipitation should occur.

What are some examples of compounds with well-known Ksp values?

Common examples include AgCl (Ksp = 1.8×10⁻¹⁰), CaF₂ (Ksp = 3.9×10⁻¹¹), and PbCl₂ (Ksp = 1.6×10⁻⁵). These values are temperature-dependent and found in chemistry reference tables.

How do temperature changes affect Ksp values?

Ksp values are temperature-dependent. For most salts, Ksp increases with temperature, meaning higher temperature increases solubility. However, some compounds like calcium sulfate show the opposite trend.