S

Solubility

Ksp = [Mn+]^m [Xn-]^n | Solubility (s) from Ksp
Quick Reference
Formula / NotationKsp = [Mn+]^m [Xn-]^n | Solubility (s) from Ksp
Also Known AsDissolution equilibrium, Saturated solution equilibrium

What is Solubility?

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

Term Solubility
Formula Ksp = [Mn+]^m [Xn-]^n | Solubility (s) from Ksp
Synonyms Dissolution equilibrium, Saturated solution equilibrium

Frequently Asked Questions

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).

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