Question

Soap does not form lather with hard water. Why? Or Why do soaps not work in hard water?​

Answer 1

Answer:

When soap is added to hard water, the Ca+2 and Mg+2 ions present in hard water react with soap. Soaps contain the sodium salts which are converted to their respective calcium and magnesium salts which are precipitated as scum. ... So, hard water does not form lather with soap.

Contains sodium ions: Contains calcium and magnesium ions

Forms foam with soap: Does not form lather, but a film is formed over the surface