Question

calculate change in heat at 25 degrees for the reaction below.

2ZnS(s) +3O2 (g) to 2ZnO(s) +2SO2 (g)

-206.0 0 -350.5 -296.8

Answer 1

S$_{2(s)}+2$ O$_{2(g)}\to2$ SO$_{2(g)}$ $\Delta\>H=-296.5kJ/mol.......(i)$

$2$ Zn$_{(s)}+$ S$_{2(s)}\to2$ Zn$_{s}$ $\Delta\>H=-206kJ/mol......(ii)$

$2$ Zn$_{s}+$ O$_{2(g)}\to2$ ZnO $\Delta\>H=-296.5kJ/mol.....(iii)$

Adding $(i)$ and $(iii)$ and reverse of $(ii)$ gives;

$2$ ZnS$_{(s)}+3$ O$_{2(g)}\to2$ ZnO$_{(s)}+2$ SO$_{2(g)}$

$\therefore2(-296.5)+2(-350)-[2(-206)]$

$=-781kJ$