In coal, pyrites `(FeS_(2))` is present as a pollution-causing impurity, which is removed by combustion.
`2FeS_(2) + 5O_(2) rarr 4SO_(2) + 2FeO`.
A process designed to remove orgainc sulphur from coal prior to combustion involves the reaction.
`X - S - Y + 2NaOH rarr X - O - Y + Na_(2)S + H_(2) O`
`CaCO_(3) rarr CaO + CO_(2)`
`Na_(2)S + CO_(2) + H_(2)O rarr Na_(2) CO_(3) + H_(2) S`
`CaO + H_(2)O rarr Ca (OH)_(2)`
`Na_(2) CO_(3) + Ca(OH)_(2) rarr CaCO_(3) + 2NaOH`
In the processing in 320 metric tons of a coal having 1.0% sulphur content, how much limestone `(CaCO_(3))` must be edecomposed to provied enough `Ca (OH)_(2)` to regenerate the `NaOH` used in the original leaching step?

Options

A. 2.0 metric ton
B. 4.0 metric ton
C. 8.0 metric ton
D. 10.0 metric ton

Answer

D

Explanation

Weight of `CaCO_(3) = (320 xx 10^(6) g "coal")`
`((1.0 g S)/(100 g "coal"))((1 "mol"S)/(32 g S))`
`((1 "mol" CaCO_(3))/("mol" S))((100 g CaCO_(3))/("mol"CaCO_(3)))`
`= (320 xx 10^(6) xx 1 xx 1 xx 1 xx 100)/(100 xx 32)`
`= 10 xx 10^(6) g CaCO_(3)`
= 10 metric ton `CaCO_(3)`