QJEEM22Ch38fd: JEE Main 2022 Chemistry - Class 11 JEEM22Ch38fd Solution: 40% of HI undergoes decomposition to H 2 and I 2 at 300 K. G…

$\therefore$ $K = {{{{\left( {{\alpha \over 2}} \right)}^{1/2}} \times {{\left( {{\alpha \over 2}} \right)}^{1/2}}} \over {(1 - \alpha )}}$

Given $\alpha = {{40} \over {100}} = 0.4$

$\therefore$ $K = {{{{\left( {{{0.4} \over 2}} \right)}^{1/2}} \times {{\left( {{{0.4} \over 2}} \right)}^{1/2}}} \over {(1 - 0.4)}}$

$= {1 \over 3}$

We know,

$\Delta G^\circ = - RT\ln K$

$= - RT\ln \left( {{1 \over 3}} \right)$

$= + RT\ln 3$

$= + 8.314 \times 300 \times \ln 3$

= 2735 J/mol