Chemistry - Thermodynamics - II Question with Solution | TestHub

Calculate the sum of the standard molar entropy changes (in J/K) of reactions (a) and (b) at 298 K:

(a) $2\mathrm{Al}(s)+\frac{3}{2}{\mathrm{O}}_2(\mathrm{g})\to {\mathrm{Al}}_2{\mathrm{O}}_3(\mathrm{s})$

(b) ${\mathrm{CaCO}}_3(\mathrm{s})+2{\mathrm{HNO}}_3(\mathrm{aq})\to \mathrm{Ca}({\mathrm{NO}}_3{)}_2(\mathrm{aq})+{\mathrm{H}}_2\mathrm{O}(\mathrm{l})+{\mathrm{CO}}_2(\mathrm{g})$

Given $S^{\circ }$ (J/K/mol): $\mathrm{Al}(s)=28.3$, ${\mathrm{O}}_2(\mathrm{g})=205.0$, ${\mathrm{Al}}_2{\mathrm{O}}_3(\mathrm{s})=50.9$, ${\mathrm{CaCO}}_3(\mathrm{s})=92.9$, ${\mathrm{HNO}}_3(\mathrm{aq})=146.4$, $\mathrm{Ca}({\mathrm{NO}}_3{)}_2(\mathrm{aq})=193.2$, ${\mathrm{H}}_2\mathrm{O}(\mathrm{l})=69.9$, ${\mathrm{CO}}_2(\mathrm{g})=213.7$.