APEF Chemistry 12
(January 2001)
Multiple Choice Questions – 40 points – Approximately 40 minutes
_A_ 1.
Which process involves the largest difference in heat content between reactants and products?
A. H2(g) ¼ H2(l) + heat
C. H2(l) + heat ¼ H2(g)
B. H2(g) ¼ H2(s) + heat
D. H2(l) ¼ H2(s) + heat
_C_ 2. What quantity of heat is evolved when 5.550 mol H2O(l) is formed from the combustion of H2(g) and
O2(g)?
H2(g) + ½ O2(g) ¼ H2O(l)
∆H = -285.8 kJ
A. 51.44 kJ
B. 285.8 kJ
C. 1586 kJ
D. 2297 kJ
_B_ 3. As energy is added to a substance, the temperature remains constant. How may the substance be
changing?
A. from a gas to a solid
C. from a liquid to a solid
B. from a liquid to a gas
D. in the amount of kinetic energy
_B_ 4. The addition of 9.54 kJ of heat is required to raise the temperature of 225.0 g of a liquid
hydrocarbon from 20.5ºC to 45.0ºC. What is the heat capacity of this hydrocarbon?
A. 0.94 J/gºC
B. 1.73 J/gºC
C. 1.88 J/gºC
D. 9.42 /gºC
_D_ 5. Which statement is true concerning this reaction:
2SO3(g) ¼ 2SO2(g) + O2(g)
A. The reaction is exothermic.
B. The reaction container would feel warm.
C. 198 kJ are given off as 2.00 g of SO3 react.
D. 198 kJ are needed to produce 2.00 mol of SO2.
∆H = 198 kJ
_D_ 6. Which of the following processes is exothermic?
A. calcium carbonate decomposing
C. ice melting
B. ether evaporating
D. steam condensing
_C_ 7. Which statement concerning these equations is correct?
(1) K(s) + ½ Br2(l) ¼ KBr(s)
∆H = -394 kJ
(2) K(s) + ½ Br2(g) ¼ KBr(s)
∆H = -416 kJ
A. Both reactions are endothermic.
B. For each mole of KBr(s) formed in reaction (2), 416 kJ of heat is absorbed.
C. If reaction (1) occurs in an insulated container, the temperature in the container will rise.
D. In both reactions, the heat content of the KBr(s) is more than that of the reactants.
_B_ 8. What is the value of ∆H for the reaction 2A + BC ¼ A2B + C given the following equations?
2A + B ¼ A2B
∆H = -217.3 kJ
B + C ¼ BC
∆H = -867.5 kJ
A. +1084.8 kJ
B. +650.2 kJ
C. -650.2 kJ
D. -1084.8 kJ
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_D_ 9. In a gas phase reaction between two molecules, what results if the molecules collide with
insufficient energy and with an unsuitable orientation with respect to each other?
A. The molecules decompose into small particles.
B. The molecules form an activated complex but then fall apart reforming the same molecules.
C. The molecules react but at a much slower rate.
D. The molecules bounce off one another with no reaction.
_C_ 10. On the potential energy diagram shown, which letter labels the activation energy for the reverse
reaction?
A. a
B. b
C. c
D. d
_D_ 11. What results when the temperature of the reaction vessel increases?
A. a decrease in the activation energy
B. an increase in the activation energy
C. an increase in the amount of product formed if the reaction is exothermic
D. an increase in the frequency of collisions
_A_ 12. What results from the addition of a catalyst to a reaction mixture?
A. a decrease in the energy required to activate the reaction
B. a decrease in the frequency of effective collisions
C. an increase in the activation energy of the reaction
D. an increase in the total yield of the products of the reaction
_C_ 13. What are two conditions necessary to establish a dynamic equilibrium?
A. constant temperature and open system
B. open system and reversible reaction
C. reversible reaction and closed system
D. variable temperature and reversible reaction
_A_ 14. Which of the following equilibria would be affectewd by volume changes at constant temperature.
1.
C2H4(g) + H2(g) ' C2H6(g)
2.
4NH3(g) + 5O2(g) ' 2NO(g) + 6H2O(l)
3.
SO3(g) + NO(g) ' NO2(g) + SO2(g)
A. 1 and 2 only
B. 1 and 3 only
C. 2 and 3 only
D. 1, 2, and 3
_C_ 15. How could the equilibrium concentration of H2 in this reaction be increased?
H2(g) + I2(g) ' 2HI
A. add a catalyst
C. decrease the amount of I2
B. decrease the amount of HI
D. decrease the pressure
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_A_ 16. Which equation has this equilibrium constant expression?
K = [Ni2+]
[Co2+]
2+
2+
A. Ni(s) + Co (aq) ' Ni (aq) + Co(s)
C. Ni2+(aq) + Co2+(aq) ' NiCo4+(aq)
B. Ni2+(aq) + Co(s) ' Ni(s) + Co2+(aq)
D. Ni2+(aq) + Co2+(aq) ' NiCo4+(s)
_A_ 17. If 1.0 mol of N2, 3.0 mol of H2, and 4.0 mol of NH3 are at equilibrium in a 1.0 L container, what is
the numerical value of the equilibrium constant?
N2(g) + 3H2(g) ' 2NH3(g)
A. 0.59
B. 1.3
C. 1.7
D. 5.3
_B_ 18. If 0.20 mol of H2O2 and 0.40 mol of CO are in equilibrium with 0.30 mol of H2O in a 1.00 L
container, what is the equilibrium concentration of CO2?
H2O2(g) + CO(g) ' H2O(g) + CO2(g)
K = 0.38
A. 0.0091
B. 0.10
C. 0.70
D. 1.4
_B_ 19. What is indicated by a large equilibrium constant for a reaction?
A. Less product is produced for a given amount of reactant at equilibrium.
B. More product is produced for a given amount of reactant at equilibrium.
C. The reaction will proceed faster to equilibrium.
D. The reaction will proceed slower to equilibrium.
_D_ 20. In the reaction, how are NO3-(aq) ions classified?
H3O+(aq) + NO3-(aq) ' HNO3(aq) + H2O(l)
A.
B.
Arrhenius acid
Arrhenius base
C.
D.
Brønsted-Lowry acid
Brønsted-Lowry base
_B_ 21. Which statements are characteristic of acids?
1. They turn blue litmus red.
2. They react with bases to produce a salt and hydrogen.
3. They taste sour.
4. They neutralize bases.
A. 1 and 4
B. 1, 3, and 4
C. 2 and 4
D.
_C_ 22. What is the definition of an Arrhenius acid?
A. ionizes completely when dissolved in water
B. ionizes in water to produce Cl-, NO3-, SO42- or similar negative ions
C. produces hydrogen ions when dissolved in water
D. produces hydroxide ions when dissolved inwater
_B_ 23. In the reaction, how are NH4+(aq) ions classified?
A.
B.
HCl(aq) + NH3(aq) ' NH4+(aq) + Cl-(aq)
conjugate acid of HCl
C. conjugate base of HCl
conjugate acid of NH3
D. conjugate base of NH3
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2, 3, and 4
_A_ 24. Acetic acid and formic acid are two weak acids; however, formic acid is a stronger acid than acetic
acid. Which statement is true?
A. Acetic acid is less ionized than formic acid in water.
B. Solutions of 1.0 mol/L acetic acid have a lower pH than those of 1.0 mol/L formic acid.
C. Formic acid is 100% ionized in aqueous solution.
D. The formate ion is a stronger base than the acetate ion.
_A_ 25. Which acts as an amphoteric species in aqueous solution?
A. HCO3B. HNO3
C. PO43-
D.
SO42-
_C_ 26. If a 0.1 mol/L solution has a pH of 4, what is the solution likely to be?
A. a strong acid B. a strong base C. a weak acid
D. a weak base
_C_ 27. What is the [H3O+] in a 0.2 mol/L NaOH(aq) solution?
A. 2 x 10-1 mol/L
B. 5 x 10-7 mol/L
C. 5 x 10-14 mol/L
D.
2 x 10-14 mol/L
_B_ 28. For 10 mL samples of aqueous solutions of these acids, which contains the largest concentration of
OH-(aq) ions?
A.
0.10 mol/L H3PO4
0.30 mol/L HBr
HBr
B.
Ka = 7.0 x 10-3
Ka = very large
HCN
0.15 mol/L H2SO4
0.30 mol/L HCN
C. H3PO4
Ka = large
Ka = 6.2 x 10-10
D. H2SO4
_C_ 29. What is the pH of a solution made by mixing 100 mL of 0.10 mol/L HNO3(aq) with 50 mL of 0.20
mol/L NaOH(aq)?
A. 0.7
B. 1.0
C. 7.0
D. 13.3
_A_ 30. Which type of titration is represented by this curve?
A.
B.
C.
D.
strong acid-strong base
strong acid-weak base
weak acid-strong base
weak acid-weak base
A_
31. what is always involved in oxidation?
A. electron transfer
C. oxygen
B. formation of oxides
D. proton transfer
_B_ 32. During an oxidation-reduction reaction, what happens to the reducing agent?
A. It accepts electrons
C. It is reduced
B. It is oxidized
D. Its oxidation number decreases
_C_ 33. Which statement is true for this reaction?
Mg + CuSO4 ¼ MgSO4 + Cu
A. Copper is oxidized
C. Magnesium is the reducing agent
B. Magnesium is reduced
D. The sulfate ion is the oxidizing agent
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_D_ 34. What is the oxidation number of chromium in K2Cr2O7?
A. -3
B. +2
C. +3
D.
+6
_B_ 35. Which statement is true for this reaction?
2I-(aq) + Br2(l) ¼ 2Br-(aq) + I2(s)
A. The I- ion is oxidized; its oxidation number decreases.
B.
C.
D.
The I- ion is oxidized; its oxidation number increases.
The I- ion is reduced; its oxidation number decreases.
The I- ion is reduced; its oxidation number increases.
_D_ 36. Which equation represents the correct oxidation half-reaction for this reaction?
Zn(s) + 2HCl(aq) ¼ ZnCl2(aq) + H2(g)
A. 2Cl-(aq) ¼ Cl2(g) + 2eC. Zn2+(aq) + 2e- ¼ Zn(s)
B.
2H+(aq) + 2e- ¼ H2(g)
D.
Zn(s) ¼ Zn2+(aq) + 2e-
_D_ 37. In an electrolytic cell, what is the reaction at the cathode called?
A. hydrolysis
B. ionization
C. oxidation
D.
reduction
_C_ 38. The diagram shows the electrolysis of molten KCl. What occurs when the switch is closed?
A.
B.
C.
D.
Positive ions move toward the anode and gain electrons.
Positive ions move toward the anode and lose electrons.
Positive ions move toward the cathode and gain electrons.
Positive ions move toward the cathode and lose electrons.
_D_ 39. Based on the table of reduction potentials, which reaction occurs spontaneously?
A. 2Ag(s) + 2H+(aq) ¼ 2Ag+(aq) + H2(g)
B. Cu(s) + 2H+(aq) ¼ Cu2+(aq) + H2(g)
C. Hg(l) + 2H+(aq) ¼ Hg2+(aq) + H2(g)
D. Mg(s) + 2H+(aq) ¼ Mg2+(aq) + H2(g)
_A_ 40. If 25.0 mL of 0.500mol/L NaOH(aq) is diluted to a final volume of 1.00 L, what is the concentration
of the diluted solution?
A. 0.0125 mol/L
B. 0.0150 mol/L
C. 0.0500 mol/L D. 20.0 mol/L
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48. Case Study: Ammonia
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