Question

Without consulting and references, predict whether each of the following reactions corresponds to an increased or decreased system entropy. Then place them in order of increasing entropy change.

a) S(s) + O2(g) → SO2(g) c) CO(g) + 3 H2(g) → CH4(g) + H2O(l)

b) H2(g) + O2(g) → H2O2(l) d) C(s) + H2O(g) → CO(g) + H2(g)

Answer 1

Entropy means disorder. Increase in entropy occurs if number of gaseous products is more than number of gaseous reactants.

a) no change in entropy (one reactant and one product is gaseous.)

b) decrease in entropy ( 2 gaseous reactants changing to one gaseous product)

c) lare decrease in entropy ( 3 gaseous reactants changing to one gaseous reactant)

d) increase in entropy ( 1 gaseous reactant changing to 2 gaseous products)

Order: c<b<a<d