For the reaction 2NO2( g)⇌2NO(g)+O2( g), when Kp and Kc are compared at 184 °C, it is found that (Given that R=0.00831 kJ mol-1 K-1.)

A
$K_{p} = K_{c}$
B
Whether $K_{p}$ is greater than, less than or equal to $K_{c}$ depends upon the total gas pressure
C
$K_{p}$ is greater than $K_{c}$
D
$K_{p}$ is less than $K_{c}$

Solution:

The expression relating $K_{p}$ and $K_{c}$ is $K_{p} = K_{c} (R T)^{Δ v_{g}}$ where $Δ v_{g}$ is the change in the stoichiometric numbers of gaseous species in the chemical equation when reactants are converted into products. For the given reaction, $Δ v_{g} = + 1$ Hence

$(R T)^{Δ v_{g}} = (8.314 J K^{- 1} {mol}^{- 1}) (457 K) = 3799.5 J {mol}^{- 1}$

Since $K_{p} = K_{c} (3799.5 J {mol}^{- 1})$ it follows that $K_{p} > K_{C}$

For the reaction $2 {NO}_{2} (g) ⇌ 2 NO (g) + O_{2} (g)$ , when $K_{p}$ and $K_{c}$ are compared at 184 °C, it is found that (Given that $R = 0.00831 kJ {mol}^{- 1} K^{- 1}$ .)

Solution:

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