What is the formula of sulphuric acid?

The formula of sulphuric acid is H2SO4. Each molecule contains two hydrogen atoms, one sulfur atom, and four oxygen atoms. “Sulphuric” is the British spelling; “sulfuric” is the preferred American and IUPAC spelling.

Sulfuric acid is a strong mineral acid and is also known historically as oil of vitriol. It is a colorless, viscous liquid that readily absorbs water from the air. Its powerful dehydrating and oxidizing properties make concentrated acid highly corrosive.

The formula is often confused with sulfurous acid, H2SO3, which contains one fewer oxygen atom and has different chemical properties. Sulfuric acid is widely used in fertilizer production, petroleum refining, chemical manufacturing, and lead-acid batteries.

Mixing sulfuric acid with water releases substantial heat. For safety, acid should be added slowly to water—not water to concentrated acid—because sudden boiling can cause dangerous splashing.