Why do soaps not work in hard water?give proper reason for it plz.

Hard water is water with lots of dissolved calcium and magnesium salts in it. Typically hard water comes from artesian wells or from water collected in limestone country. Normally when soap is mixed with water, sodium stearate is produced which quickly releases stearate into the water to act as the bridging agent between the oil and water.

When hard water is mixed with soap two salts are formed, calcium stearate and magnesium stearate, both of which are insoluble in water. Thus instead of free stearates being released into the water, a scum of calcium and magnesium stearate forms instead and the soap does not work.

soaps dont work in hard water because hard water contain calcium and mg salts and soap is sodium or potassium salt of 17-18 carbon fatty acids. ca and mg salts from hard water react with sodium or potassium to form ca salts of fatty acids.these ca and mg salts are not capable of washing and form precipitaes.