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Sodium Hypochlorite

Sodium hypochlorite (commonly known in a dilute solution as bleach) is a chemical compound with the formula NaOCl It is mainly used as a bleaching and disinfecting agent and is commonly found in household bleach. Sodium hypochlorite is generally used dissolved in water at various concentrations.

Synonyms
Antiformin, Bleach, Chloride of soda
Chemical Formula
NaOCl
CAS Number
7681-52-9 (anhydrous)

Characteristics

Molar Weight
74.439g/mol
Boiling Point
101 °C
Density
1.11 g/cm3
Forms
Liquid

Uses and Applications

Key applications

  • Disinfectant
  • Wastewater treatment
  • Cleaning products
  • Fuel additive
  • Agricultural
  • Laundry products
  • Bleaching agent

Industries

Sodium hypochlorite

Sodium hypochlorite is known in everyday life under the names bleach or chlorine bleaching lye, but is also called hypochlorous sodium, "Eau de Labarraque", "Eau de Javel", Javel's lye or antiformin. The empirical formula of the substance is NaOCl. Sodium hypochlorite is the sodium salt of hypochlorous acid (HClO). In its crystallisation form when free of water, it is quite fragile and is then used in its solid state as sodium hypochlorite pentahydrate. Mostly, however, sodium hypochlorite is traded as an aqueous solution. Sodium hypochlorite is used worldwide as a bleaching agent and disinfectant in various industries, for example in the pharmaceutical, cleaning, water treatment or lubricants sectors.
Properties of sodium hypochlorite
NaOCl is produced by electrolysis of a sodium chloride solution or by introducing chlorine gas into a sodium hydroxide solution. Sodium hypochlorite is soluble in water. It crystallises from the aqueous solution at -10 degrees Celsius as a crystalline water-rich and colourless solid. When sodium hypochlorite is heated to room temperature, it reacts with water loss to form relatively stable, pale yellow sodium hypochlorite pentahydrate.
Cropped shot of a woman cleaning a kitchen counter at home

Sodium hypochlorite in the household

Sodium hypochlorite is the main ingredient of disinfectant and bleaching household cleaners; mould removers and pipe cleaners also contain the substance. It reacts alkaline as a solution and dissolves fats and proteins by saponification or denaturation and subsequent hydrolysis.
Sodium hypochlorite also has an oxidising effect. The products are often advertised in the trade as "with active chlorine". They contain about five to seven percent of the chemical.
Pharmacist researching medication

Sodium hypochlorite in medicine

Sodium hypochlorite is used in dentistry. For example, it is used in a diluted solution (0.5 to 5 per cent) in the root canal treatment of bacterially infected teeth in order to disinfect them and to exclude inflammatory foci. In ophthalmology, it is used to disinfect the measuring instruments in glaucoma.
Sodium hypochlorite is a proven surface disinfectant that is not suitable for hand disinfection because it can cause skin irritation. However: During the SARS-CoV-2 pandemic, sodium hypochlorite was also used in hand disinfectants due to the lack of disinfectants.

Other uses of sodium hypochlorite

Sodium hypochlorite is used in 10- to 13-percent concentrations under the name "liquid chlorine" or "chlorine liquid" for disinfecting swimming pools. When disinfecting pools with the chemical, a sufficiently high dosage must be selected in order to chlorinate ammonia sufficiently. At the same time, skin irritation of visitors must of course be avoided.