Question

For the reaction, $2NOCl\left(g\right)\rightleftharpoons 2NO\left(g\right)+C{l}_2\left(g\right);K_c$ at ${427}^{\circ }$ is $3\times {10}^{-6}$. The value of $K_p$ is nearly:

• A. $7.50\times {10}^{-5}$
• B. $2.50\times {10}^{-5}$
• C. $2.50\times {10}^{-4}$
• D. $1.72\times {10}^{-4}$

Answer 1

The correct option is D $1.72\times {10}^{-4}$

The relation between $K_p$ and $K_c$ is as follows:
$K_P=K_C(RT{)}^{\Delta n}$
$\Delta n=$change in gaseous moles.
For the reaction, $2NOCl\left(g\right)\rightleftharpoons 2NO\left(g\right)+C{l}_2\left(g\right)$,
$K_C=3\times {10}^{-6}$ L/mol, $R=0.0821$ Latm/K mol, $\Delta n=3-2=1$
$T=427+273=700K$
$K_P=3\times {10}^{-6}(0.0821\times 700{)}^1$ $=1.72\times {10}^{-4}$.
Therefore, the value of $K_p$ is $1.72\times {10}^{-4}$.