Calculate the Entropy change.
1. From the following Ho and So values predict which of reactions I, II, and III will be spontaneous at 300ºC.
|
|
H (kJ)
|
S(J/K)
|
|
I
|
-5.0
|
-15
|
|
II
|
-10.0
|
+20
|
|
III
|
-5.0
|
-30
|
A.I
B.II
C.III
D.I and II
E.II and III
2. From the following Ho and So values predict which of reactions I, II, and III would be spontaneous at 25ºC.
|
|
H (kJ)
|
S(J/K)
|
|
I
|
+10.5
|
+30
|
|
II
|
+1.8
|
-113
|
|
III
|
-126
|
+84
|
A.I
B.II
C.III
D.I and II
E.II and III
3. Work out the entropy change (J/mole.K) of the reaction. The molar entropies [S] are given in brackets
after each substance.
2 CuS(s) [66.5] + 3 O2(g) [205.1]" 2 CuO(s) [42.6] + 2 SO2(g) [248.2]
A.-114.2
B.-139.1
C.+33.0
D.+68.2
E.+166.7
4.. Calculate the entropy change (J/mole.K) of the reaction. The molar entropies [S] are given in
brackets after each substance.
3 NO2(g) [240.1] + H2O(l) [69.9] " 2 HNO3(aq) [146.4] + NO(g) [210.8]
A.-286.6
B.-212.4
C.-156.3
D.+47.2
E. +156.3
5.Given Sº = -266.3 and the listed [Sº values] calculate Sº for Fe3O4(s).
4 Fe3O4(s) [____] + O2(g) [205.1] " 6 Fe2O3(s) [87.4]
A.+111.1
B.+122.4
C.+134.1
D.+146.4
E.+159.6