In the laboratory of a school, the sample of hard water is not available “to study the comparative cleaning capacity of a sample of soap in soft and hard water”. Which salt from the laboratory can be added to tap water to make it hard ? In the experiment how is cleaning capacity of soap compared ?
Salt: Sulphate, Chloride or hydrogen Carbonate of Calcium or Magnesium (any one)
By adding equal amount of soap to water taken in two test tubes, shaking vigorously and comparing the length of lather or foam formed in each test tube.