Definitions
Sodium hypochlorite NaClO

"Bleach and bleaching agents" are aqueous solutions of sodium hypochlorite NaClO, usually obtained by reacting chlorine with caustic soda. These solutions also contain sodium chloride NaCl formed during the reaction:$2\text{NaOH}+{\text{Cl}}_2\to \text{NaClO}+\text{NaCl}+{\text{H}}_2\text{O}$

with ΔH = – 103.2 kJ/mole Cl₂

In the past, the concentration of bleach and bleach extracts was expressed in French-speaking countries in chlorometric degrees and elsewhere by the amount of active chlorine. The number of chlorometric degrees was the number of liters of chlorine gas that could be released from one liter of solution under...