Question

At $300 \,K$, the value of $(\frac{K_c}{K_p})$ will be lowest for

• A. $N_2(g) + O_2 (g) \ce{<=>} 2NO(g)$
• B. $N_2(g) + 3H_2 (g) \ce{<=>} 2NH_3(g)$
• C. $PCl_5(g) \ce{<=>} PCl_3(g) + Cl_2(g)$
• D. $2HI(g) \ce{<=>} H_2(g) + I_2 (g)$

Answer 1

Answer: (C)

$K_{p}=K_{c}\left(RT\right)^{\Delta n} \Rightarrow \frac{K_{c}}{K_{p}}=\left(RT\right)^{-\Delta n}$
1. $N_{2}+O_{2} {\rightleftharpoons} 2NO, \Delta n=0, \frac{K_{c}}{k_{p}}=1 $
2. $N_{2}+3H_{2} {\rightleftharpoons} 2NH_{3}, \Delta n =-2, \frac{K_{c}}{K_{p}}=\left(RT\right)^{2}$
3. $PCl_{5} {\rightleftharpoons} PCl_{3}+Cl_{2}, \Delta n=1, \frac{K_{c}}{K_{p}}=\left(RT\right)^{-1}$
4. $2HI {\rightleftharpoons} H_{2}+I_{2}, \Delta n=0, \frac{K_{c}}{K_{p}}=1$