Question

Soap forms a precipitate in hard water. Give scientific explanation.

Answer 1

Yes, Soaps form precipitate in hard water known scuum (Insoluble substance). That's why soaps doesn't work in hard water.

Reason/Explanation :-

We know that, Hard water contains high amount of Magnesium and calcium ions , when it reacts with soaps it forms insoluble substance.

While soap is made up of long chain of fatty acids by Sodium (Na) and Potassium(K) salts .

So it is clear that when soaps are added in hard water, Hard water ions displace sodium and potassium from it's salts.  


Reaction Which is Involved in the process :-

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C₁₇H₃₅COONa + CaCl₂ ----→ C₁₇H₃₅(COO)₂Ca + 2NaCl
 Soap                                         Insoluble
(Sodium Stearate)               (Calcium Stearate)     
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Hence , Soap is added to hard water forms Insoluble substance(Precipitate). That is why soap is insoluble in hard water.    



Hope it Helps :-)