Question

A sample of $ HI_{(g)} $ is placed in a flask at a pressure of $ 0.2 $ atm. At equilibrium, partial pressure of $ HI_{(g)} $ is $ 0.04 $ atm. What is $ K_p $ for the given equilibrium ?
$ 2HI_{(g)} \rightleftharpoons H_{2(g)} +I_{2(g)} $

• A. $ 0.04 $
• B. $ 0.4 $
• C. $ 40 $
• D. $ 4 $

Answer 1

Answer: (D)

$0.2-2x=0.04$
$\Rightarrow 2x=0.2-0.04$
$x=0.08\,atm$
$K_{p}=\frac{\left(0.08\right)\left(0.08\right)}{\left(0.04\right)^{2}}=4$