Question

$\Delta G(HI:g)\equiv +1.7kJ.$ What is the equilibrium constant at ${25}^{o}C$ for $2HI\left(g\right)\rightleftharpoons H_2\left(g\right)+I_2\left(g\right)$?

• A. 24
• B. 3.9
• C. 2
• D. 0.5

Answer 1

The correct option is C 2

given $2HI\rightleftharpoons H-2\left(g\right)+I_2\left(g\right)$ eq. constant $K$ at ${25}^{o}C$

$\Delta G=1.7$ $kJ$

we know $\Delta G=RTln$ $K$

$1.7\times {10}^3=2.303logK\left(RT\right)$

$1700=2.303\left(8.314\right)\left(298\right)logK$

$logK=\frac{1700}{2.303\times 8.314\times 298}=\frac{1700}{5706}$

Hence $logK$ = $0.29$

$K=1.94\approx 2$