You Asked:
How does bleach work? — James, Moline, Ill.

Marshall Answered:
Good old chlorine bleach like you find in the laundry room is sodium hypochlorite or NaClO. People typically use bleach for two things: 1) to remove stains, and 2) to kill microorganisms.

When bleach mixes with water it forms hypochlorous acid, or HClO. This acid is devastating to bacteria and many viruses because it denatures proteins and DNA. It will kill bacteria in less than a second. A 1% bleach solution will disinfect counter tops and dishes. Bleach added to drinking water or swimming pool water kills all bacteria.

The stain-removing feature of bleach comes from bleach’s ability to modify chromophores. A chromophore is the part of a molecule that gives it its color. Bleach can break or reform bonds in the chromophore and eliminate its ability to produce color. For details see: How does chlorine bleach work?