For the equilibrium: `CaCO_(3(s)) iff CaO_((s)) + CO_(2(g)) , K_p = 1.64` atm at 1000 K, 50 g of `CaCO_3` in a 10 litre closed vessel is heated to 1000 K. Percentage of `ĆaCO_3` that remains unreacted at equilibrium is (Given R=0.082 L atm `K^(-1) "mol"^(-1)`).

Options

A. 40
B. 50
C. 60
D. 20

Answer

C

Explanation

For the reaction,
`CaCO_(3(s)) hArr CaO_((s))+CO_(2(g))`
`K_(c)=[CO_(2)]` or `K_(p)=P co_(2)`
No. of moles of `CaCO_(3(s))=("Mass")/("Mol. Mass")`
`=(50)/(100)=0.5`
Applying ideal gas equation,
`PV=nRT`
`1.64xx10=nxx0.082xx1000`
No. of moles of `CO_(2),n=0.2`
No. of moles of unreacted `CaCO_(3)=0.5-0.2=0.3`
% of unreacted `CaCO_(3)=(0.3)/(0.5)xx100=60%`