In chemistry, protonation (or hydronation) is the adding of a proton (or hydron, or hydrogen cation), (H+) to an atom, molecule, or ion, forming a conjugate acid. (The complementary process, when a proton is removed from a Brønsted–Lowry acid, is deprotonation.) Some examples include * The protonation of water by sulfuric acid:H2SO4 + H2O ⇌ H3O+ + HSO−4 * The protonation of isobutene in the formation of a carbocation:(CH3)2C=CH2 + HBF4 ⇌ (CH3)3C+ + BF−4 * The protonation of ammonia in the formation of ammonium chloride from ammonia and hydrogen chloride:NH3(g) + HCl(g) → NH4Cl(s)