Cleansing Agents

Soap and (synthetic) detergent are the two everyday chemical tools for cleansing, and although they do the same practical job, they are built from different chemistry. Soap, chemically speaking, is the sodium or potassium salt of a higher (long-chain) fatty acid. Detergent instead is the sodium salt of either an alkyl hydrogen sulphate or an alkyl benzene sulphonic acid. That difference in the underlying acid group -- a carboxylic acid for soap, a sulphate or sulphonate group for detergent -- turns out to explain a very practical difference in performanc …