Question

$40^{\circ }$ of $HI$ undergoes decomposition to $H_2$ and $I_2$ at $300K.\Delta G^{\ominus }$ for this decompostion reaction at one atmosphere pressure is ____$Jmo{l}^{-1}$. [nearest integer]
(Use $R=8.31J{K}^{-1}mo{l}^{-1};\log 2=0.3010$. In $10=2.3,\log 3=0.477$)

Answer 1

Answer: 2735

teq $1-0.4\frac{0.4}{2}\frac{0.4}{2}$
$K_p=\frac{(0.2{)}^{\frac{1}{2}}(0.2{)}^{\frac{1}{2}}}{1-0.4}=\frac{0.2}{0.6}=\frac{1}{3}$
$\Delta G=\Delta G^{\circ }+RT\ln K=0$
$\Delta G^{\circ }=-RT\ln K$
$\Rightarrow -8.31\times 300\times 2.3\times \log \left(\frac{1}{3}\right)$
$=2735J/mol$