Question

A sample of $CaC{O}_3\left(s\right)$ is introduced into a sealed container of volume 0.821 litre & heated to 1000 K until equilibrium is reached. The equilibrium constant for the reaction $CaC{O}_3\left(s\right)\rightleftharpoons CaO\left(s\right)+C{O}_2\left(g\right)$ is $4\times {10}^{2}atm$ at this temperature. Calculate the mass of CaO present at equilibrium

• A. $112$ mg
• B. $224$ mg
• C. $448$ mg
• D. None of these

Answer 1

The correct option is B $224$ mg

The equilibrium constant expression is $K=P_{C{O}_2}=4\times {10}^2$ atm.

The number of moles of carbon dioxide can be calculated from ideal gas equation.

$n=\frac{PV}{RT}=\frac{4\times {10}^2\times 0.821}{0.0821\times 1000}=4$

The number of moles of $CaO$ is equal to the number of moles of carbon dioxide. it is equal to $4$ moles.

The molar mass of $CaO$ is $56$ g/mol.

The mass of $CaO$ present is $4\times 56=224$ g