Question

What is the equilibrium constant expression for the reaction,
$P_4\left(s\right)+5O_2\left(g\right)\rightleftharpoons P_4{O}_{10}\left(s\right)$

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

Answer 1

Answer: (D)

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

The equilibrium constant expression for the reaction,
$P_4\left(s\right)+5O_2\left(g\right)\rightleftharpoons P_4{O}_{10}\left(s\right)$ is $K_c=\frac{1}{{\left[O_2\right]}^5}$
Note: The concentrations of solids (and pure liquids) are considered unity and do not appear in the equilibrium constant expression.