Question

Calculate the standard entropy change for the reaction at 25 °C. Standard molar entropy values can be found in this table.

H2O(g)+C(graphite)(s)⟶H2(g)+CO(g)

Answer 1

Here we can find the standard value of entropy from the table in which it is given that

$\Delta S_f(C)=5.59,\Delta S_f(H_2O)=188.72,\Delta S_f(CO)=197.9 ,\Delta S_f(H_2)=130.59$

Entropy change for the reaction can be calculated as follows

$\Delta S_{rxn}= (\Delta S_f(CO) + \Delta S_f(H_2))-(\Delta S_f(C) + \Delta S_f(H_2O))$

$\Delta S_{rxn}=(197.9+130.59)-(5.59+188.72)$

$\Delta S_{rxn}=134.08$ J/K