Question

$H_2+I_2\to 2HI$

What is the $K_{eq}$ for the reaction shown above if $H_2=1$ atm, $I_2=2$ atm and $HI=3$ atm?

• A. $0.33$
• B. $3$
• C. $0.22$
• D. $0.67$
• E. $4.5$

Answer 1

The correct option is E $4.5$

$\bullet$ For any general reaction

xA + yB $\to$ zC + wD.

$K_{eq}=\frac{{\left[C\right]}^z{\left[D\right]}^w}{{\left[A\right]}^x{\left[B\right]}^y}$

$\bullet$ For gaseous equilibrium

Concentration is directly propostional to the partial pressure of the gaseous component.

$\Rightarrow {H_2}_{\left(9\right)}+{I_2}_{\left(9\right)}⟶{2HI}_{\left(9\right)}$

$K_{eq}=\frac{{\left[P_{HI}\right]}^2}{\left[{P_H}_2\right]\left[{P_I}_2\right]}=\frac{3^2}{\left[1\right]\left[2\right]}$

$\therefore$ value of $K_{eq}$ = 4.5