Question

Consider following reactions:

(a) $2ZnS+3O_2\to 2ZnO+2S{O}_2$

$ZnO+C\to Zn+CO$

(b) $2ZnS+C\to 2Zn+C{S}_2$

Which reaction has more positive value of $\Delta G$?
1. A
2. B
3. A and B are same
4. None

Answer 1

As $C{O}_2$ & CO are more stable than $C{S}_2$ so

$2ZnS+3O_2\to 2ZnO+2S{O}_2$

$ZnO+C\to Zn+CO$

is much more spontaneous reaction than B.

And as we know,

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

As A is more spontaneous reaction so it will have higher negative value of G.

So, B have higher positive value of G.