Question

What is the entropy change (∆S) for the reaction: 2H2(g) + O2(g) → 2H2O(l) given the standard entropy values ∆S°(H2(g)) = 130.6 J/K·mol ∆S°(O2(g)) = 205.0 J/K·mol ∆S°(H2O(l)) = -69.9 J/K·mol

Answer 1

To calculate the entropy change  S  for the reaction, we need to consider the stoichiometry of the reaction and the standard entropy values of the reactants and products. The general formula for calculating the entropy change is:S = nS products  - nS reactants For this reaction:S = [2  S H2O l  ] - [2  S H2 g   + S O2 g  ]Plugging in the given standard entropy values:S = [2   -69.9 J/Kmol ] - [2   130.6 J/Kmol  +  205.0 J/Kmol ]S = [-139.8 J/Kmol] - [261.2 J/Kmol + 205.0 J/Kmol]S = -139.8 J/Kmol - 466.2 J/KmolS = -606.0 J/KmolThe entropy change  S  for the reaction is -606.0 J/Kmol.