Question

explain the formation of scum when hard water is treated with soap....
answer please!!!!!
science 10th cbse

Answer 1

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✴ Soaps are sodium or potassium salts of higher fatty acids. Hardness in water is due to the presence of Ca^2+ and Mg^2+ ions, present as their salts. The soap first reacts with calcium abd magnesium ions to form insoluble precipitate of calcium and magnesium salts of fatty acids which float as an off- white layer over wated. This layer is called scum.



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Answer 2

When a soap is used in hard water a solid substance we call scum forms. This is because charged calcium and magnesium particles called ions present in the water react with soap to form an insoluble substance. The new substance scum does not dissolve in water.