M2SO4

M2SO4 is the general chemical formula used to denote salts formed from sulfuric acid with monovalent cations, such that two cations accompany one sulfate anion (SO4^2-). It describes a family of compounds rather than a single substance. Common examples include sodium sulfate (Na2SO4), potassium sulfate (K2SO4), and ammonium sulfate ((NH4)2SO4).

In these salts, the sulfate unit remains the sulfate ion, while the surrounding cations are typically arranged in an ionic lattice. Some members of the M2SO4 family form crystalline hydrates; for example, sodium sulfate can occur as the decahydrate Na2SO4·10H2O. Physical properties such as solubility and hydration state vary with the specific cation.

Preparation of M2SO4 salts is usually by neutralization or metathesis reactions. Examples include reacting a metal hydroxide with sulfuric acid (2 MOH + H2SO4 → M2SO4 + 2 H2O) or reacting a metal carbonate with sulfuric acid. Ammonium sulfate can be prepared by neutralizing sulfuric acid with ammonia (2 NH3 + H2SO4 → (NH4)2SO4).

Uses and significance vary by cation. Many M2SO4 salts are soluble and have industrial roles: ammonium sulfate is a widely used fertilizer; potassium and sodium sulfates find use in fertilizers, glass manufacture, and as processing aids or drying agents in diverse industries. They are generally considered to have low toxicity, though handling precautions apply for dust and solutions.