Question

For a reaction $M_2{O}_{\left(s\right)}\to 2M_{\left(s\right)}+\frac{1}{2}{O}_{2\left(g\right)},$ $\Delta H$ $=$0.07 kJ/mol /K at 1atm. The reaction would not be spontaneous at temperatures:

• A. $>429K$
• B. $<429K$
• C. $<100K$
• D. $>100K$

Answer 1

Answer: (B)

$<429K$

$\Delta G=\Delta H-T\Delta S$
for non spontaneous reaction $\Delta G>0$
$\Delta H-T\Delta S>0$
$\frac{\Delta H}{\Delta S}>T$
$\frac{30}{0.07}>T$
$T<429K$