Sulphate ion (SO₄²⁻)

Sulphate ion (SO₄²⁻)

A compound ion produced when sulphuric acid releases a proton.



sulphate ion, acidic residue ion, anion, ion, compound ion, sulphuric acid, sulphates, gypsum, blue vitriol, inorganic chemistry, chemistry

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Sulphate ion SO₄²⁻


Molar mass: 96.1 g/mol

Molecular shape: regular tetrahedron

Bond angle 109.5°


The sulphate ion is a compound ion bound by covalent bonds, which carries two negative electrical charges. The pi bonds are delocalised within the ion. It forms salts with metal ions and the ammonium ion. Most sulphates dissolve well in water (except the barium, strontium, lead and calcium sulphates).

Sulphate ions are formed from sulphuric acid with the loss of two protons. Barium ions are used in the qualitative and quantitative determination of sulphate ions. Barium ions form a white, insoluble barium sulphate precipitate with sulphate ions. The most important sulphates are copper sulphate, gypsum and Glauber's salt.


Sodium aluminium sulphate, known as soda alum, is used as an acidity regulator in the food industry. Calcium sulphate (or gypsum) is used as blackboard chalk and in medicine. Hydrated copper sulphate is used as a fungicide, gypsum as support for broken limbs, and Glauber´s salt in the production of glass and in medicine.



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