Question

15000 litres of hard water was passed through a zeolite softener. The exhausted zeolite required 120 litres of NaCI having stream of 30g/l of NaCL Calculate the hardness of water.

Answer 1

1 litre of NgCl solution            = 30 gm of NaCl.
∴ 120 litre of NaCl                   = 120x30x10³ mg of NaCl.
∴  3600 x10³ mg of NaCl.        = 3600 x10³ x `50/58.5`

                                                `= 30.7692 xx  10^5 "mg of " CaC0_3 ` equivalent.
15000 litres of water               ` = 30.7692 xx10^5 " mg of" CaC0_3` equivalent.
∴ 1 litres of water                    = `(30.7692 xx10^5)/15000`  = 205.1 ppm

∴  Hardness of water samQ.Ie = 205. 1 ppm