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Explain the formation of scum when hard ...

Explain the formation of scum when hard water is treated with soap.

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Hard water often contains salts of calcium and magnesium. Soap molecules react with the salts of calcium and magnesium and form a precipitate. This precipitate begins floating as an off-white layer over water. This layer is called scum. Soaps lose their cleansing property in hard water because of formation of scum.
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Explore conceptually related problems

(a) Write structure of ethanol. Give chemical equation of its reaction with (i) sodium (ii) excess conc H_2SO_4 at 443 K. (b) (i) Write your observation, if you dip a red litmus paper in soap solution. (ii) Explain the formation of scum in hard water. (iii) Suggest one method to remove the temporary hardness of water. 1

What problem does arise when hard water is treated with soap ?

Knowledge Check

  • There is no scum formation when hard water is being used The washing powder can be

    A
    `C_(17)H_(35)COONa`
    B
    C
    Both
    D
    None of these

  • There is no scum formation when hard water is being used. The washing powder can be

    A
    `C_(17)H_(35)COONa`
    B
    C
    Both
    D
    None

  • Statement I : Hard water does not give lather with soap . Statement II : Calcium and magnesium salts present in hard water form precipitate with soap .

    A
    Both the statements individually true and Statement II is the correct explanation of Statement I.
    B
    Both the statements are individually true but Statement II is not correct explanation of Statement I.
    C
    Statement I is true but Statement II is false .
    D
    Statement I is false but Statement II is true .

    • Similar Questions

    Explore conceptually related problems

    (a) You have three unlabelled test tubes containing ethanol, ethanoic acid and soap solution. Explain the method you would use to identify the compounds in different test tubes by chemical tests using litmus paper and sodium metal. (b) Give the reason of formation of scum when soaps are used with hard water.

    Why does hard water not form lather with soap ?

    Why does hard water not from lather with soap ?

    Why hard water does not give lather with soap?

    Assertion : Soft water lathers with soap but not hard water. Reason : Hard water reacts with soap to form insoluble salts which form scum, not lather.

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