100 " mL of " tap water was titrated with `(M)/(50)` HCl with methyl orange as indicator if 30 " mL of " HCl were required, calculate the hardness of `CaCO_3` per `10^(5)` parts of water. The hardness is temporary.

Explanation

For temporary hardness:
`Ca(HCO_(3))_(2)+2"HCl"toCaCl_(2)+2CO_(2)+2H_(2)O`
`2 " mol of "HCl-=1 " mol of "Ca(HCO_(3))_(2)`
`-=1 " mol of "CaCO_(3)(100 parts)`
`1 mol or 1 " Eq of "HCl-=50g of CaCO_(3)`
`1 " mL of " NHCl-=0.05 g of CaCO_(3)`
`30" mL of " (M)/(50)(=(N)/(50))HCl`
`-=(30)/(50)xx0.05 g of (CaCO_(3))/(100mL) of H_(2)O`
`-=0.03g (CaCO_(3))/(100mL) of tap H_(2)O`
`-=(0.3xx10^(5))/(100)=30g of CaCO_(3)`