Question

For the reaction,

$2N{O}_2\left(g\right)\rightleftharpoons 2NO\left(g\right)+O_2\left(g\right)$

[$K_c=1.8\times {10}^{-6}$ at 184${}^o$C and R = 0.00831 kJ/mol K]

When $K_p$ and $K_c$ are compared at 184${}^o$C, it is found that:

• A. Whether $K_p$ is greater than or less than or equal to $K_c$, it depends upon the total gas pressure
• B. $K_p=K_c$
• C. $K_p$ is less than $K_c$
• D. $K_p$ is greater than $K_c$

Answer 1

The correct option is D $K_p$ is greater than $K_c$

$2N{O}_2\left(g\right)\rightleftharpoons 2NO\left(g\right)+O_2\left(g\right)$

$K_c=1.8\times {10}^{-6}$ at ${184}^{o}C(=457K)$

$R=0.00831kJmo{l}^{-1}{K}^{-1}$

$K_p=K_c(RT{)}^{\Delta n_g}$

where,

$\Delta n_g=$ (gaseous products - gaseous reactants)

$=3-2=1$

$\therefore K_p=1.8\times {10}^{-6}\times 0.00831\times 457$

$=6.836\times {10}^{-6}>1.8\times {10}^{-6}$

Thus, $K_p>K_c$