Sodium Hypochlorite (Bleach) (NaClO) — Properties, Uses & Safety

Overview

Sodium hypochlorite (NaClO) is an inorganic compound with a molar mass of 74.44 g/mol, best known as the active ingredient in household bleach. In aqueous solution, it appears as a pale greenish-yellow liquid with a characteristic chlorine-like odor. Sodium hypochlorite is an ionic compound consisting of sodium cations (Na+) and hypochlorite anions (ClO−). The hypochlorite ion is a powerful oxidizing agent — it works by releasing nascent oxygen and chlorine species that destroy the cell membranes and proteins of bacteria, viruses, and fungi, making it one of the most effective and widely used disinfectants in the world. Household bleach typically contains 3–8% sodium hypochlorite in water, while industrial-strength solutions can reach 10–15%. Common applications include laundry bleaching, surface disinfection, water treatment and purification, swimming pool sanitation, and mold remediation. Sodium hypochlorite is produced industrially by the chloralkali process, where chlorine gas is dissolved in a sodium hydroxide solution: Cl2 + 2 NaOH → NaClO + NaCl + H2O. This reaction itself is a great teaching example of a disproportionation reaction, where chlorine is simultaneously oxidized and reduced. GHS hazard codes include H290 (may be corrosive to metals), H314 (causes severe skin burns and eye damage), H335 (may cause respiratory irritation), and H400/H410 (very toxic to aquatic life with long-lasting effects). A critical safety warning: never mix bleach with ammonia (produces toxic chloramine gases) or with acids (releases deadly chlorine gas). For chemistry students, sodium hypochlorite illustrates oxidation-reduction chemistry, disproportionation reactions, the chemistry of halogens, solution concentration calculations (dilution problems), and real-world chemical safety. It connects classroom redox chemistry to everyday household products and public health.

IUPAC Name

sodium hypochlorite

CAS Number

7681-52-9

PubChem CID

23665760

Molecular Formula

NaClO

Molar Mass

74.44 g/mol

State at STP

solid

Appearance

Pale greenish-yellow liquid (in aqueous solution)

Physical Properties

Density

1.11 g/cm³

Composition