Question

What is the value for ∆Soreaction for the following reaction, given the standard entropy values? Fe2O3(s) + 3H2(g) 2 Fe(s) + 3H2O(g)

Answer 1

Answer: 141.55 J/K

Explanation: Value of ΔS can be obtained as:  

$\Delta S=\sum{\text {Entropy of Products}-\sum{\text {Entropy of Reactants}}$

Standard entropy values are

$S^o(Fe_2O_3)=87.4J/molK$

$S^o(H_2)=130.59J/molK$

$S^o(Fe)=27.28J/molK$

$S^o(H_2O)=188.72J/molK$

$Fe_2O_3(s)+3H_2(g)\rightarrow 2Fe(s)+3H_2O(g)$

$\Delta S=\sum(2\times 27.28J/molK+3\times 188.72J/molK)-(3\times 130.59J/molK+1\times 87.4J/molK)=141.55J/K$