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Sodium hypochlorite (Household bleach)

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  • Sodium hypochlorite (Household bleach)

    We have many questions about household bleach dilution. The subject is complex for two reasons:

    *It is not a simple solution of sodium hypochlorite and water, but also sodium hydroxide and sodium chloride. Typical production methods produce equimolar concentrations of NaCl and NaOCl, and typically leave sufficient excess NaOH to keep pH in 11-12 range to improve storage.

    *Concentration is described in at least five different ways, both weight/weight, and weight/volume. The actual sodium hypochlorite concentration may be given or the equivalent "available chlorine." One mole of sodium hypochlorite (NAOCl) is equivalent to one mole of chlorine gas (Cl2) in a common reference reaction which liberates iodine.

    Two useful references:

    Commercial sodium hypochlorite does degrade over time decreasing NaOCl concentration and increasing NaCl concentration. However, based on the equimolar assumption at time of manufacture and molar masses, the initial NaCl concentration should be about 78.5% of the NaOCl concentration, when specified on weight/volume basis.