Question

The hardness of 85000 litres of water sample was removed by passing it through a zeolite softener. The zeolite required 2000 litres of NaCl solution containing 190 mg/lit of NaCl for regeneration. calculate the hardness of sample.

Answer 1

1 litres of NaCl solution  = 190 mg of NaCl

∴ 2000 litres of NaCl      =  2000 x 190 gm of NaCl

                                      =  3,80,000 gm of NaCl.

Quantity of NaCl in terms of CaC0₃ equivalent hardness.

                                     =  3,80,000 xx 5/58.5 gm of CaC0₃ equivalen,

                                     =  3,24,786.3 gm ofCaC0₃ equivalent

                                     = 324.79 x10³ gm of CaC0₃ equivalent

                                    = 324.79 x10⁶ gm of CaC0₃ equivalent

Hardness of 85000 litres of water = 324. 79x10⁶ gm

∴ Hardness of 1 litre  = `(324.79 xx 10^6)/85000 3821` mg/litre

∴ Hardness of water   = 3821 mg/lit

                                    = 3821 ppm.