Answer
a. $\Delta$S$^{\circ}$= -186 J/K x mol$rxn$
b.$\Delta$S$^{\circ}$= 187 J/K x mol$rxn$
c. $\Delta$S$^{\circ}$= 348 J/K x mol$rxn$
Work Step by Step
a. 2$H_{2}$S +S$O_{2}$ -> 3 $S_{rhombic}$ + 2 $H_{2}O$
$\Delta$ S$^{\circ}$= Sum of S$^{\circ}$ (Products) - Sum of S$^{\circ}$ (Reactants)
$\Delta$ S$^{\circ}$= 3 S$^{\circ}$ (S) +2 S$^{\circ}$ ($H_{2}O$)- S$^{\circ}$ (S$O_{2}$)- 2 S$^{\circ}$ ($H_{2}S$)
$\Delta$ S$^{\circ}$=3 S$^{\circ}$ (32) +2 S$^{\circ}$ (189)- S$^{\circ}$ (248)- 2 S$^{\circ}$ (206)
$\Delta$S$^{\circ}$= -186 J/K x mol$rxn$
b. 2S$O_{3}$ -> 2S$O_{2}$ +$O_{2}$
$\Delta$ S$^{\circ}$= Sum of S$^{\circ}$ (Products) - Sum of S$^{\circ}$ (Reactants)
$\Delta$ S$^{\circ}$= 2 S$^{\circ}$ (S$O_{2}$)- S$^{\circ}$ ($O_{2}$)- 2 S$^{\circ}$ (S$O_{3}$)
$\Delta$ S$^{\circ}$= 2 S$^{\circ}$ (248)- S$^{\circ}$ (205)- 2 S$^{\circ}$ (257)
$\Delta$S$^{\circ}$= 187 J/K x mol$rxn$
c. $Fe_{2}$$O_{3}$ + 3$H_{2}$ -> 2 Fe + 3$H_{2}O$
$\Delta$ S$^{\circ}$= Sum of S$^{\circ}$ (Products) - Sum of S$^{\circ}$ (Reactants)
$\Delta$ S$^{\circ}$= 2 S$^{\circ}$(Fe) +3 S$^{\circ}$ ($H_{2}O$)- 3 S$^{\circ}$ ($H_{2}$) - S$^{\circ}$ ($Fe_{2}$$O_{3}$)
$\Delta$ S$^{\circ}$= 2 S$^{\circ}$(108) +3 S$^{\circ}$ (189)- 3 S$^{\circ}$ (115) - S$^{\circ}$ (90)
$\Delta$S$^{\circ}$= 348 J/K x mol$rxn$