The cleansing action of soap in hard water is not satisfactory because soap
Answer Details
Soap is made up of sodium or potassium salts of long-chain fatty acids. The cleaning action of soap is due to its ability to dissolve in water and attach to oil and dirt particles, enabling them to be washed away. However, in hard water, which contains dissolved calcium and magnesium ions, soap forms insoluble salts with these ions. These salts, called scum, are insoluble in water and stick to surfaces, reducing the effectiveness of the soap. As a result, the cleansing action of soap in hard water is not satisfactory.