Question

For the reaction : $X_2{O}_4\left(l\right)\to 2X{O}_2\left(g\right)$. $\Delta U=2.1kcal,\Delta S=20cal{K}^{-1}at300K$.
Hence $\Delta G$ is:

• A. $-7kcal$
• B. $-4.7kcal$
• C. $+2.7kcal$
• D. $-2.7kcal$

Answer 1

The correct option is D $-2.7kcal$

As we know,

$\Delta H=\Delta U+\Delta n_{g}RT$

$=2.1+2\times 0.002\times 300=3.3kcal$

$\Delta G=\Delta H-T\Delta S$

$=3.3-300\times \left(0.02\right)=-2.7kcal$