Question

When $20g$ of $CaC{O}_3$ was put into a $10$ litre flask and heated to ${800}^{\circ }C,15\%$ of $CaC{O}_3$ remained unreacted at equilibrium. Calculate $K_p$ for the decomposition of $CaC{O}_3$.

Answer 1

$CaC{O}_3\to CaO+C{O}_2$

No of moles of $CaC{O}_3=\frac{w}{M.W.}=\frac{20}{100}=0.2$ moles

ATQ

$35\%$ of $CaC{O}_3$ remains unreacted

$\frac{35}{100}\times 0.2=0.07$

$\alpha =0.2-0.07$

$\alpha =0.13$

$K_c=\left[C{O}_2\right]=0.14$ [$\because \left[C{O}_2\right]=\alpha ]$

$K_p=\left(K_c\right)\times R{T}^{△n}$

$K_p=0.13\times 0.082\times 1073$

$K_p=11.438$

thus $K_p=11.438/10=1.1438$

$x=1.1438$

$1000x\approx 1145$