Sodium hypochlorite, commonly known in a dilute solution as bleach, is an inorganic chemical compound with the formula NaOCl, comprising a sodium cation and a hypochlorite anion. It may also be viewed as the sodium salt of hypochlorous acid. The anhydrous compound is unstable and may decompose explosively. It can be crystallized as a pentahydrate NaOCl·5H₂O, a pale greenish-yellow solid which is not explosive and is stable if kept refrigerated.