Q20 of 80 Page 113

How would you predict whether a given water sample is of hard water or soft water? Give chemical equation.

To determine whether a given water sample is of hard water or soft water, one can use soap.


Soap produces lather in soft water whereas soap does not produce lather in hard water due to the formation of scum (insoluble precipitate). Scum is a result of reaction of soap with calcium and magnesium ions present in the hard water.



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How is glacial acetic acid different from acetic acid provided to you in laboratory? Write its one characteristic which resembles its name.

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Soaps are prepared by treating the esters of fatty acid with alkali. Sometimes common salt is also added to it. Why is common salt added during this process?

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