Question

Ten thousand litres of hard water was made soft with zeolite. The exhausted zeolite required a total amount of 8 lit of NaCl solution containing 150 gm per litre for regeneration. Calculate the hardness of water.

Answer 1

1 litre of NaCl solution                     =   150 gm of NaCl

∴  8 litres of NaCl                             = Bx 150gm of NaCI

                                                          = 1200 gm of NaCl

Quantity of NaCl in terms ofCaCO₃ = `1200xx 50/58.5` gm of CaCO₃ equivalent

equivalent hardness

                                                        = 1,025.64 gm ofCaCO₃ equivalent

                                                        = 1. 0256 x 10³ CaCO₃ equivalent

                                                        = 1.0256 x 106 CaCO₃ equivalent.

Hardness of 10,000 litres of water   = `1,0256 xx 10^6 `mg

∴ Hardness of 1 litres                      `=(1.026 xx 10^6) /10000`102.6 mg/lit

∴ Hardness of water                    =   102.6ppm