The equilibrium constant for the dissolution of a sparingly soluble salt. For AgCl(s) ⇌ Ag⁺(aq) + Cl⁻(aq), Ksp = [Ag⁺][Cl⁻].

How is Ksp related to molar solubility?

For A_xB_y, if molar solubility is s, then [A] = xs and [B] = ys, so Ksp = (xs)^x (ys)^y = x^x y^y s^(x+y).

Why does the common ion effect reduce solubility?

Adding a common ion increases the concentration of one product, so by Le Chatelier the equilibrium shifts back toward the solid, reducing the amount that dissolves.

Will a precipitate form?

Compute the ionic product Q with the current ion concentrations and compare to Ksp. If Q > Ksp, a precipitate forms; if Q < Ksp, more can dissolve; if Q = Ksp, the solution is saturated.

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NSW · HSCChemistry

Ksp solubility product calculator

Convert between Ksp and molar solubility for any salt A_xB_y, with the equilibrium ion concentrations shown for free.

Inputs

Salt: A_xB_y dissolves as x Aⁿ⁺ + y B^m-.

x (cation count)y (anion count)

Solve forMolar solubility s (mol/L)

Result

Ksp

1.690e-10

[cation] at equilibrium

1.300e-5mol/L

[anion] at equilibrium

1.300e-5mol/L

For A_xB_y: Ksp = (xs)^x (ys)^y = x^x y^y s^(x+y).

How this calculator works

For A_xB_y dissolving to give x cations and y anions per formula unit, Ksp = x^x × y^y × s^(x+y). The calculator either raises s to compute Ksp, or takes the (x+y)th root of Ksp/(x^x y^y) to compute s.

Common questions

What is Ksp?: The equilibrium constant for the dissolution of a sparingly soluble salt. For AgCl(s) ⇌ Ag⁺(aq) + Cl⁻(aq), Ksp = [Ag⁺][Cl⁻].
How is Ksp related to molar solubility?: For A_xB_y, if molar solubility is s, then [A] = xs and [B] = ys, so Ksp = (xs)^x (ys)^y = x^x y^y s^(x+y).
Why does the common ion effect reduce solubility?: Adding a common ion increases the concentration of one product, so by Le Chatelier the equilibrium shifts back toward the solid, reducing the amount that dissolves.
Will a precipitate form?: Compute the ionic product Q with the current ion concentrations and compare to Ksp. If Q > Ksp, a precipitate forms; if Q < Ksp, more can dissolve; if Q = Ksp, the solution is saturated.