CHEM 1412 Practice exam 3
Chapter 17-19
1. The process that leads to an increase in entropy is _____.
A) Melting
B) Freezing
C) Condensation
D) Cooling
2. The process _____ has a negative entropy change.
A) 2 KClO4(s) 2 KClO3(s) + O2(g)
B) H2O(g)  H2O(l)
C) 2 Na(s) + 2 H2O(l)  2 NaOH(aq) + H2(g)
D) N2(g)  2N(g)
Q3-Q4. Oxidation is responsible for turning alcohol into vinegar:
C2H5OH(l) +
O2(g) 
HC2H3O2(l) +
ΔSo(J/K.mol) 161.0
205.0
159.8
o
ΔG (kJ/mol) -174.18
0
-389.45
3. What is the ΔSo for this reaction in J/K?
(A) –136.3
(B) + 136.3 (C) –454.9
(D) +494.9
(E) –494.9
4. What is the ΔGo for this reaction in kJ?
(A) –494.9
(B) +494.9
(C) –452.5
(E) –136.3
(D) +136.3
H2O(l).
69.9
-237.2
5. The reaction with ΔH◦ = 10.5 kJ and ΔS◦ = 30. J•K–1 will be spontaneous _____.
A) Above100K
B) Below 300 K
C) Above 350 K
D) Below 250 K
6. The standard free energy change, ΔG°, for the vaporization of water is 8.6 kJ at 25◦C. The
vapor pressure of water at 25◦C is _____ atm.
A)
0.31 B)
3.1 x10–3
C)
0.031 D)
3.1 x10–4
7. The equilibrium constant for the reaction
is 4.4 at 2000
K. The value of ΔG for the reaction when the partial pressures of H2, CO2, H2O and CO are
0.25, 0.78, 0.66 and 1.20 atm respectively is _____ kJ/mol.
A)
–110
B)
–8.1
C)
–254
D)
–1.33
8. Cu + 2H2SO4  CuSO4 + SO2 + H2O
a). Which species is the oxidizing agent?
H2SO4
b). Which species is oxidized?
Cu
c). What is the oxidation number for Cu and S in CuSO4? +2 and +6
9. When the following reaction is balanced in acidic solution, what is the coefficient of I2?
IO3– + I–  I2
A)
B)
C)
D)
1
2
3
4
10. How many electrons are transferred in the following reaction when it is balanced in acidic
solution? NO3– + I–  IO3– + NO2
A) 6
B) 2
C) 10
D) 5
E) 3
11. Which of the following is true for the cell shown here? Zn(s) | Zn2+(aq)  Cr3+(aq) | Cr(s)
A) The electrons flow from the cathode to the anode.
B) The electrons flow from the zinc to the chromium.
C) The electrons flow from the chromium to the zinc.
D) The chromium is oxidized.
E) The zinc is reduced.
12. What is the balanced chemical equation corresponding to the following cell diagram?
Na(s) | Na+(aq) || Cu2+(aq) | Cu(s)
A)
B)
C)
D)
E)
2Na(s) + 2Na+(aq)  Cu2+(aq) + Cu(s)
Cu(s) + 2Na+(aq)  2Na(s) + Cu2+(aq)
2Na(s) + Cu(s)  2Na+(aq) + Cu2+(aq)
Cu2+(aq) + Cu(s)  2Na(s) + 2Na+(aq)
2Na(s) + Cu2+(aq)  2Na+(aq) + Cu(s)
13. Which of the following is the strongest oxidizing agent?
Cl2 + 2e–  2Cl–
Mg2+ + 2e–  Mg
2H+ + 2e–  H2
A)
B)
C)
D)
E)
Cl2
H2
Mg
Mg2+
Cl-
 1.36 V
 –2.37 V
 0.00 V
14. Consider the following electrode potentials:
Mg2+ + 2e–  Mg
V2+ + 2e–  V
Cu2+ + e–  Cu+
= –2.37 V
= –1.19 V
= 0.16 V
Which one of the reactions below will proceed spontaneously from left to right?
A) Mg2+ + V V2+ + Mg
B) Mg2+ + 2Cu+  2Cu2+ + Mg
C) V2+ + 2Cu+  V + 2Cu2+
D) V + 2Cu2+  V2+ + 2Cu+
15.
The standard emf of the cell involving Mg/Mg2+ (anode) and Cu/Cu2+ (cathode) half-cell
reactions is
A)2.03V
B)1.18V
C)3.71V
D)2.71V
16. The emf of a cell consisting of a Pb/Pb2+ (0.1 M) half-cell and a Pt/H+ (0.050 M)/H2(g, 1
atm) half-cell is _____.
Two half-cell reactions:
2H+ +2e- H2 (g) (Eo= 0.00V)
Pb2+ (aq) +2e-Pb (Eo= -0.13V)
A) 0.83 V
B) 1.02 V
C) 0.43 V
D) 0.083 V
17. Using the standard reduction potential (E◦cell= 0.54V) of reaction
to find the equilibrium constant at 25°C is _____.
9
A) 5.2 x 10
B) 1.7 x 1011
C) 1.75 x 1018
D) 2.7 x 1018
18. If a constant current of 5.0 amperes is passed through a cell containing Cr3+ for 1.0 hour, how
many grams of Cr will plate out onto the cathode? (The atomic mass of Cr is 51.996.)
A) 9.7 g
B) 9.0  10 4 g
C) 3.2 g
D) 29 g
E) 6.2  10 2 g
19. What’s 1  particle?
A) Proton
B) Neutron
C) Electron
D) Positron
0
20. 'X' in the equation
A) 24
21
B)
1
1
C)
0
1
D)
0
1
is _____.
p


In the reaction
, X is _____.
A)
B)
C)
D)
16
7
N
22. An unstable isotope of rhenium, 191Re, is a beta producer. What is the other product of the
reaction?
A) 191Os
B) 191W
C) 192Pt
D) 190W
E) 190Os
23. Heavier nuclei are broken down into smaller nuclei by nuclear _____.
A) fission
B) transmutation
C) fusion
D) Oxidation