Question

The hardness of 1000 litres of a water sample was removed by passing it through a zeolite softener which required 30litres of NaCl solution containing 1.5 gm/L NaCl for regeneration. The hardness of the water sample will be ___________​

Answer 1

100g of NaCl→1 litre  

 

1g=1000mg102×103mg of NaCl→1 litre    102g105mg of Nacl→1 litre  

400 litres solution cxontains −>400×105mg of NaCl

Now,

CaCO3 equivalent =400×105×100/(2×58.5)=341.88×105mg of CaCO3 equivalent

1 litre =341.88×105ppm104 litre =xX=341.88×105×104

Hardness of water sample =341.88×109ppm

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