Question

In a study of equilibrium
H2(g)+I2(g)2HI(g)
1mol of H2 and 3 mol of I2 give rise at equilibrium to 1.5 mol of HI.
Addition of a further 2 mol of H2 gave an additional 1.5 mol of HI.
In above problem, what is $K_p$ at the temperature of the experiment.

• A. 1
• B. 2
• C. 4
• D. None of these

Answer 1

The correct option is C 4

The expression for the equilibrium constant for two equilibria will be
$K_p=\frac{[HI{]}^2}{\left[H_2\right]\left[I_2\right]}=\frac{x^2}{(1-0.5x)(3-0.5x)}=\frac{{1.5}^2}{\left(0.25\right)\left(2.25\right)}=4$
Here, $x=1.5$.