Q.
A water sample contains 22.2mg of CaCl2 in 1L of sample. The degree of hardness of water in terms of CaCO3 equivalent is ------ ppm.[ Molar mass of CaCO3=100gmol−1, molar mass of CaCl2=111gmol−1]
ppm is parts per million (106). This is equivalent to mg per litre. 1L of water contains 22.2mg of CaCl2 Now, 111g of CaCl2≡100gCaCO3 22.2mg of CaCl2=11122.2×100=20
It is equivalent to 20mg of CaCO3 in 1L of water ∴ Hardness of water sample =20ppm