Question

$2HI\left(g\right)\leftrightharpoons H_2\left(g\right)+I_2\left(g\right)$
What is the equilibrium constant expression for the above reaction?

• A. ${\left[H_2\right]}^2\left[I_2\right]$
• B. $\left[H_2\right]$
• C. $\frac{\left[H_2\right]\left[I_2\right]}{{\left[HI\right]}^2}$
• D. $\left[H_2\right]{\left[I_2\right]}^2$
• E. ${\left[H_2\right]}^2{\left[I_2\right]}^2$

Answer 1

The correct option is C $\frac{\left[H_2\right]\left[I_2\right]}{{\left[HI\right]}^2}$

Consider a general chemical reaction
$aA+bB\leftrightarrow cC+dD$
The equilibrium constant expression is
$K_c=\frac{\left[C{]}^c\right[D{]}^d}{\left[A{]}^a\right[B{]}^b}$
For following reaction equation :
$2HI\to H_2+i_2$
The equilibrium constant expression is
$K_c=\frac{\left[H_2\right]\left[I_2\right]}{[HI{]}^2}$