Question

Calculate the change in entropy for the reaction: 2H2(g) + O2(g) → 2H2O(g)if the standard entropy values of H2, O2, and H2O are 130.7 J/mol*K, 205.0 J/mol*K, and 188.7 J/mol*K, respectively.

Answer 1

To calculate the change in entropy for the reaction, we can use the formula:S_reaction = S_products - S_reactantsFor the given reaction, the reactants are 2 moles of H2 g  and 1 mole of O2 g , and the product is 2 moles of H2O g . Using the standard entropy values provided:S_reaction = [2 *  188.7 J/mol*K ] - [2 *  130.7 J/mol*K  +  205.0 J/mol*K ]S_reaction =  377.4 J/mol*K  -  261.4 J/mol*K + 205.0 J/mol*K S_reaction =  377.4 J/mol*K  -  466.4 J/mol*K S_reaction = -89.0 J/mol*KThe change in entropy for the reaction is -89.0 J/mol*K.