Question

What is the correct expression of $K_c$ for the given reaction?
$P_4\left(s\right)+5O_2\left(g\right)\leftrightharpoons P_4{O}_{10}\left(s\right)$

• A. $K_c=[O_2{]}^5$
• B. $K_c=\frac{\left[P_4{O}_{10}\right]}{\left[P_4\right][O_2{]}^5}$
• C. $K_c=\frac{\left[P_4{O}_{10}\right]}{\left[P_4\right][O_2{]}^5}$
• D. $K_c=\frac{1}{(O_2{)}^5}$

Answer 1

The correct option is D $K_c=\frac{1}{(O_2{)}^5}$

$P_4\left(s\right)+{50}_2\left(g\right)\leftrightharpoons P_4{O}_{10}\left(s\right)$

Since, the activity of solids is taken as unitiy, only gaseuos species will contribute to $K_c$

$\therefore K_c=\frac{1}{[O_2{]}^5}$