A sample of chalk (`CaCO_(3))` is contaminated with calcium sulphate 1.0 g of the solid is dissolved in 230 " mL of " `(N)/(10)` HCl, 40.1 `(N)/(10)` NaOH is requried to neutralise the excess acid. What ist he percentage of chalk in the mixture.

Explanation

`CaCO_(3)+2"HCl"toCaCl_(2)+H_(2)O+CO_(2)`
Total acid used`=230xx(N)/(10)HCl=23mEq HCl`
Excess acid`=40mL (N)/(10)NaOH=4m" Eq of "acid`
Acid used `=23-4=19m" Eq of "acid`
`=19 m" Eq of "CaCO_(3)`
`=19xx10^(-3)xx50=0.95g`
`% of CaCO_(3)=(0.95)/(1)xx100=95%`