What is the solubility product?
For a barely-soluble salt, K_sp is the product of its dissolved ion concentrations at saturation - the point where no more will dissolve. Small K_sp = very insoluble.
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Solubility Product (K_sp)
Calculate K_sp = [A⁺][B⁻] for a sparingly soluble salt, with symbol legend and real-world examples.
Ksp = [A^+][B^-]
Frequently asked questions
How does it predict a precipitate?
Compare the actual ion product with K_sp. Above K_sp, solid precipitates out until it falls back to K_sp; below, more can dissolve.
Where does it matter?
Kidney stones, kettle and pipe scale, tooth enamel dissolving in acid, and water treatment that precipitates out toxic metals. It is the chemistry of dissolved versus solid.
What is the common-ion effect?
Adding more of one of the salt's ions makes it less soluble - since the product is fixed, raising one ion forces the salt to precipitate. A chloride salt dissolves less in salty water.
How does the example give 10⁻¹⁰?
[A⁺] = 10⁻⁵ and [B⁻] = 10⁻⁵ multiply to 10⁻¹⁰ - a very small number, showing a sparingly soluble salt.