Question

a. explain in structure and words the observation that soap does not work properly in very low PH water or hard water which has calcium and magnesium ions.

b. would a soap made form N,N,N-trimethyl octadecyl ammonium chloride have thesame problems as a long chain of carboxylic acid? Explain

Answer 1

a. In order for a soap to work they must remain in the form of a salt of say sodium. When the pH is low, the salts tend to hydrolyze and form neutral carboxylic acids which are very stable at low pH. These thus cannot form the micellar structure which are required for removal of cleaning mechanism. In hard water soaps react with the Ca2+ or Mg2+ present in water and produces insoluble scum, This thus reduces the amount of froth formed and thus the effectiveness of soap is reduced. The soap must remain soluble at all times for maximum efficiency.

b. A soap made from N,N,N-trimethyloctadecyl ammonium chloride will not have the problem of getting hydrolyzed and produce a neutral compound when in low pH aqueous medium. It is basic at all times even when in neutral form (NH) and thus would be soluble in water. It will not even react with Ca2+ and Mg2+ salts to produce insolble salts and thus would not have the same problems as a long chain carboxylic acid.