A mixture of iron (II) and lead (II) caerbonates was calcined. As a result of thisk, an amount of 0.9 " mol of "`CO_(2)` was evolved. The mixture of metal oxides obtained by decomposing the above carbonates was treated with sulphuric acid, which, resulted in a mass of 151.6 g of a sulphate as precipitate. Determine the composition of the starting mixture of carbonates in mass percentage.

Explanation

(a). `FeCO_(3)toFeO+CO_(2)`
`PbCO_(3)toPbO+CO_(2)`
(b). `FeO+H_(2)SO_(4)toFeSO_(4)+H_(2)O`
`PbO+H_(2)SO_(4)toPbSO_(4)darr+H_(2)O`
Only `PbSO_(4)ppt=151.6`
Let x " mol of "`FeCO_(3)` and y " mol of "`PbCO_(3)`
Therefore, moles of `CO_(2)=x+y=0.9`
Moles of `PbSO_(4)=` moles of PbO `=y`
`y=(151.6)/(303(Mw of PbSO_(4)))=0.5`
`thereforex=0.4`
Mass of `FeCO_(3)=0.4xx116=46.9g=25.79%`
Mass of `PbCO_(3)=0.5xx267=133.5g=74.2%`