The maximum amount of a solute that can dissolve in a given amount of solvent at a specified temperature. Expressed as g/100 mL or mol/L. Solubility depends on temperature (usually increases for solids, decreases for gases) and pressure (important for gases).
Formula & Notation
Ksp = [Mn+]^m [Xn-]^n | Solubility (s) from Ksp
Other Names / Synonyms: Dissolution equilibrium, Saturated solution equilibrium
Properties & Characteristics
Solubility product (Ksp): equilibrium constant for dissolution of slightly soluble salt. If ion product Q > Ksp: precipitation occurs. If Q < Ksp: unsaturated (dissolves more). If Q = Ksp: saturated. Temperature effects: most solid solubilities increase with T; gas solubility decreases with T (Henry's Law: C = kH × P). Common Ksp values (25°C): AgCl = 1.8×10⁻¹⁰, BaSO₄ = 1.1×10⁻¹⁰, CaCO₃ = 3.4×10⁻⁹, PbS = 9.0×10⁻²⁹.
Uses & Applications
Qualitative analysis (selective precipitation to identify ions). Water treatment (precipitating heavy metals as hydroxides or sulfides). Antacid chemistry (CaCO₃ dissolving in stomach acid). Kidney stone formation (CaC₂O₄, struvite). Scale formation in pipes (CaCO₃, CaSO₄). Pharmaceutical: choosing appropriate salt forms for bioavailability. Geological: mineral formation and dissolution.
Safety Information
Low solubility does not mean low toxicity — many sparingly soluble compounds are highly toxic (e.g., lead sulfate, mercuric sulfide). Barium compounds (BaSO₄ safe for X-rays; BaCl₂ highly toxic). Always check toxicity data regardless of solubility. Precipitation of toxic heavy metals during wastewater treatment requires careful pH control.
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
TermSolubility
FormulaKsp = [Mn+]^m [Xn-]^n | Solubility (s) from Ksp
The maximum amount of a solute that can dissolve in a given amount of solvent at a specified temperature. Expressed as g/100 mL or mol/L. Solubility depends on temperature (usually increases for solids, decreases for gases) and pressure (important for gases).
Qualitative analysis (selective precipitation to identify ions). Water treatment (precipitating heavy metals as hydroxides or sulfides). Antacid chemistry (CaCO₃ dissolving in stomach acid). Kidney stone formation (CaC₂O₄, struvite). Scale formation in pipes (CaCO₃, CaSO₄). Pharmaceutical: choosing …
Low solubility does not mean low toxicity — many sparingly soluble compounds are highly toxic (e.g., lead sulfate, mercuric sulfide). Barium compounds (BaSO₄ safe for X-rays; BaCl₂ highly toxic). Always check toxicity data regardless of solubility. Precipitation of toxic heavy metals during wastewat…
The formula or notation for Solubility is: Ksp = [Mn+]^m [Xn-]^n | Solubility (s) from Ksp
Editorial standards: Chemical data is sourced from peer-reviewed literature,
CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA,
and IAEA. For educational purposes only — always consult official SDS documentation and qualified
professionals before handling chemicals.
