Expert: Henry Boyter - 11/6/2005

Question
I am not a student,  I'm old. I work for a softwater service part time and we use a varity of chemicals. My question is why does sodium hypochlorite form a basic solution when mixed with water?

Thanks

Answer
From http://en.wikipedia.org/wiki/Sodium_hypochlorite

Hydrolysis is just the reaction with water.  The sodium hydroxide is a stronger base than hypochlorous is an acid, so you get a basic solution.


"Like all hypochlorites, sodium hypochlorite is a salt of hypochlorous acid, HClO. Sodium Hypochlorite is a colorless, transparent liquid. In water, it partially splits into the sodium cation Na+ and the hypochlorite anion ClO-, while a substantial portion hydrolyses into sodium hydroxide and hypochlorous acid. The oxidizing power of the latter and of the hypochlorite anion cause the bleaching effect. Its negative charge, however, prevents it from diffusing through the cell walls of bacteria and microbes, making it a poor disinfectant. However the hypochlorous acid molecules that exist in equilibrium with the hypochlorite anion, due to their neutral charge and small size, easily diffuse through the cell walls of bacteria. This changes the oxidation-reduction potential (ORP) of the cell, and inactivates the enzyme triosephosphate dehydrogenase. Triosephosphate dehydrogenase (or glyceraldehyde-3-phosphate dehydrogenase/GAPDH) is essential for the digestion of glucose, but is particularly sensitive to oxidising agents. Its inactivation effectively destroys the micro-organism's ability to function."