Question

Equimolar quantities of $HI,H_2,I_2$ are brought to equilibrium. If the total pressure in the vessel is $1.5atm$ and $K_p$ for the reaction
$2{HI}_{\left(g\right)}\rightleftharpoons H_{2\left(g\right)}+I_{2\left(g\right)}$ is $49$
Which of the following is the correct value for the equilibrium partial pressure of $I_2$?

• A. $0.4$
• B. $0.9$
• C. $0.7$
• D. $0.5$

Answer 1

The correct option is C $0.7$

$2H{I}_{\left(g\right)}\rightleftharpoons H_2\left(g\right)+I_2\left(g\right)$

initial $2p$ $0$ $0$

at eqlbm $2p-2x$ $x$ $x$

$K_p=\frac{x.x}{(2p-2x{)}^2}$

$2p-2x+x+x=1.5$

$p=0.75atm$

$4g=\frac{x^2}{(1.5-2x{)}^2}$

$x=0.7atm$