Question

For a reaction $N{H}_{4}COON{H}_{2\left(s\right)}\rightleftharpoons 2N{H}_{3\left(g\right)}+C{O}_{2\left(g\right)}$, the equilibrium pressure is $3$ atm. $K_p$ for the reaction will be :

• A. $27$
• B. $4$
• C. $3$
• D. $9$

Answer 1

The correct option is B $4$

The given reaction is:-

${NH}_{4}COO{NH}_2\left(s\right)\rightleftharpoons 2{NH}_3\left(g\right)+{CO}_2\left(g\right)$

$\because$ Volume & temperature are constant, so no. of mole of gas & its partial pressure.

Now, $Kp=P_{{NH}_3}^2.{Pco}_2$ (${NH}_{4}COO{NH}_2$ is pure solid)

Now, $P_{{NH}_3}\propto 2p\left(Let\right)\Rightarrow P_{{CO}_2}\propto p$

Now, at eqm, Total pressure $=3$ atm

$\Rightarrow 2p+p=3atm\Rightarrow p=1atm$

$\Rightarrow Kp={\left(2p\right)}^2\times p={4p}^3=4\times {\left(1\right)}^2=4{atm}^3$