How do test a given water sample is soft or hard ?

pH of a water sample is tested with

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Degree of hardness of a water sample is 100ppm. If that sample contains hardness causing salt Mg(HCO_3)_2 , calculate weight of Ca(OH)_2 required for the treatment of 10kg of water sample.

A hard water sample contains magnesium bicarbonate only. 100 ml of the hard water sample requires 10 ml. of standard soap solution (1 ml soap solution = 1 mg CaCO_3 ) to get good lather. Find out of the weight of Ca(OH_2) to be added to 10 Kg water sample to make it soft water.

Hardness of a water sample is 150 ppm. Its hardness is due to only calcium bicarbonate, the weight of calcium hydroxide that required to remove hardness of one litre of hard water is

Do you find any change in colour and smell of water in some water samples? What are your reasons?

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