1 litre water sample of ground water in an area is found to contain 7.3 mg of `Mg(HCO_(3))` and `1.11 mg` of `CaCl_(2)`. Express the hardness of water in that area.

Explanation

Total weight of `CaCO_(3)`
146 g of `Mg(HCO_(3)) = 100 g` of `CaCO_(3)`
`7.3 xx 10^(-3) g = ?`
`rArr (100 xx 7.3 xx 10^(-3))/(146) = 5 xx 10^(-3)`
111g of `CaCl_(2) = 100g` of `CaCO_(3)`
`1.11 xx 10^(-3)g = ?`
`rArr (100 xx 1.11 xx 10^(-3))/(111) = 10^(-3)`
`rArr 5 xx 10^(-3) +1 xx 10^(-3) rArr 6 xx 10^(-3)`
Hardness `=(6 xx 10^(-3))/(1000) xx10^(6) = 6 p pm`