931_2nd Exam_931117
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) If the concentration of Na+ in an aqueous solution of sodium sulfate is 3.2 × 10-1 mol/L, how many
moles of sodium sulfate must have been dissolved per liter to make the solution?
A) 9.6 × 10-1
B) 1.6 × 10-1
C) 1.1 × 10-1
D) 3.2 × 10-1
E) 6.4 × 10-1
1)
2) Which of the following has the highest total concentration of ions?
A) 0.05 M HBr
B) 0.1 M NaCl
C) 0.04 M (NH4 )2 SO4
2)
D) 0.03 M Al2(SO4 )3
E) 0.1 M CH3 OH
3) Consider 0.1 M solutions of the following substances. Which would have the greatest electrical
conductivity?
A) CH3COOH
3)
B) HCl
C) NH4 Br
D) Ca(OH)2
E) CH3NH2
4) Which of the following is incorrectly labeled?
A) HCOOH - weak electrolyte
B) NH3 - weak electrolyte
4)
5) In an electrolysis experiment an electric current is passed into an aqueous solution. Which one of
the following substances would you add?
A) C2 H5 OH
B) CH4
C) CO2
D) CCl4
E) NH4 NO3
5)
6) Which of the following substances is a weak electrolyte in aqueous solution?
A) HNO3
6)
C) HCl - strong electrolyte
D) KCl - strong electrolyte
E) HNO2 - strong electrolyte
B) CH3COOH
C) NaOH
D) NH4 NO3
E) HCl
7) Which one of the following substances would you expect to be a nonelectrolyte in aqueous
solution?
A) HBr
B) CH3CH2 OH
C) KI
D) CH3COOH
E) NH3
1
7)
8) A 25.00 mL sample of an aqueous solution of Ba(OH)2 requires 18.45 mL of 0.01500 M HCl (aq) for
8)
its neutralization. What is the molarity of the Ba(OH)2 solution?
A) 6.919
B) 13.84
C) 0.02214
D) 5.535 × 10-3
E) 0.01107
9) How many liters of a 3.85 M solution of Fe2+ are needed to titrate 250.0 mL of a 0.125 M
9)
2CrO 4 solution?
H+ + CrO42- + Fe2+
A) 4.06
B) 4.87
Fe3+ + Cr2O3 + H2 O
C) 8.12
(not balanced)
D) 0.0487
E) 0.0244
10) Use the solubility rules to predict which of the following substances is insoluble in water.
A) Hg2 Cl2
B) Cs2 SO4
C) LiBr
D) NH4 CrO4
E) Pb(NO3)2
10)
11) Which reactions will not produce a precipitate from aqueous solution?
A) ZnCl2 + (NH4 )2S
11)
B) NaBr + Al2 (SO4)3
C) FeSO4 + Ba(OH)2
D) Hg2 (NO3 )2 + KI
E) Pb(NO3)2 + Na2 CO3
12) The net ionic equation that describes what happens when solutions of Ba(OH)2 and NaNO3 are
mixed is:
A) Ba2+ (aq) + 2 OH- (aq)
12)
Ba(OH)2 (s)
NaOH (s)
B) Na+ (aq) + OH- (aq)
+
NaNO 3 (s)
C) Na (aq) + NO3 (aq)
Ba(NO3)2 (s)
D) Ba2 + (aq) + 2 NO3 (aq)
E) none of the above
13) Which reaction type is incorrectly labeled?
NH4 + (aq), neutralization
A) NH3 (aq) + H+ (aq)
B) CH4 (g) + 2 O2 (g)
CO2 (g) + 2 H2 O (g), oxidation-reduction
3+
2AlPO4 (s), precipitation
C) Al (aq) + PO4 (aq)
Zn2+ (aq) + H2 (g), oxidation-reduction
D) Zn (s) + 2 H+ (aq)
E) Ba2+ (aq) + SO42- (aq)
BaSO4 (s), neutralization
2
13)
14) When the following reaction is balanced under acidic conditions, the coefficient of water is:
Mn2+ (aq) + MnO4 - (aq)
14)
MnO2 (s)
A) 1 on left
B) 2 on left
C) 0, H2O doesn't appear in the balanced equation.
D) 1 on right
E) 2 on right
15) Which of the following reactions is not a redox reaction? Some of the reactions may not be
balanced.
A) 2 Al + Fe2O3
2 Fe + Al2 O3
B) H+ + OHC) NH3 + NO
D) Bi3+ + Fe3+
E) Ni2+ + Fe3+
H2 O
N2 + H 2 O
BiO3 - + Fe2+
Fe2+ + Ni
16) Which of the following unbalanced half reactions illustrates an oxidation?
IA) I2
B) Al
C) Fe3+
D) NO
E) MnO2
15)
16)
Al2 O3
Fe2+
N2
Mn2+
17) Which statement is incorrect regarding oxidation?
A) Oxidation is the combination with O atoms.
B) Oxidation is an increase in oxidation state.
C) Oxidation is always accompanied by reduction.
D) Oxidation is a "gain" of electrons.
E) none of these
17)
18) Considering the following reaction, what statement is incorrect?
18)
Cu (s) + 4 H+ (aq) + 2 NO3 - (aq)
Cu2+ (aq) + 2 NO2 (g) + 2 H2 O (l)
A) Cu is oxidized.
B) Cu2 + is the result of an oxidation.
C) NO3 - is reduced.
D) NO3 - is the oxidizing agent.
E) Cu is the oxidizing agent.
3
19) Zn lies above Pb in the activity series of metals. Which of the following statements is correct?
A) Zn will react with Pb.
B) Zn2 + will react with Pb.
19)
C) Pb2 + will react with Zn2+.
D) Pb will react with Zn2+ .
E) Zn will react with Pb2+.
20) In the reaction Cl2 (aq) + 2 I- (aq)
A) I-.
B) Cl2 .
2 Cl- (aq) + I2 (aq), the oxidizing agent is
C) Cl- .
D) H2 O.
20)
E) I2.
21) What is the pressure, in atm, exerted by ocean water (density = 1.05 g/cm3) at a depth of 1000 m?
The density of mercury is 13.6 g/cm3 and the density of pure water is 1.00 g/cm3.
21)
22) Volume and temperature are directly proportional. If T is plotted in °C, what is the temperature
when the volume is negligible?
A) -40
B) 0
C) -273
D) 100
E) depends on the gas
22)
23) Consider four identical 1.0-L flasks containing the following gases each at 0°C and 1 atm pressure.
Which sample has the most molecules?
A) NH3
23)
A) 102
B) 96.7
C) 182
D) 10.2
E) 967
B) SO2
C) O2
D) H2
E) same for all gases
24) Which of the following pairs involve variables that are inversely proportional?
A) V, n
B) P, n
C) n, T
D) V, T
E) P, T
24)
25) The volume of a gas is 36.0 mL at 10.0°C and 4.50 atm. At what temperature (°C) will the gas have a
pressure of 3.50 atm and a volume of 85.0 mL?
A) 246°C
B) 220°C
C) 623°C
D) 77.7°C
E) 896°C
25)
26) Equal moles of H2, N2 , O2 , and He are placed into separate containers at the same temperature.
26)
Assuming each gas behaves ideally, which container has the highest pressure?
A) N2
B) O2
C) He
D) H2
E) They would all exhibit the same pressure.
4
27) Consider the following gas phase reaction:
27)
2 NO + O2
2 NO 2
400. mL of NO at STP is reacted with 500. mL of O2 at STP. Calculate the volume of the reaction
mixture at STP after the reaction goes to completion.
A) 700 mL
B) 100 mL
C) 1300 mL
D) 800 mL
E) 900 mL
28) Consider the following reaction:
28)
2 NO + O2
2 NO 2
200. mL of NO at STP is reacted with 500. mL of O2 at STP. Calculate the partial pressure of NO2
after the reaction goes to completion. Assume a constant volume.
A) 1.00 atm
B) 0.286 atm
C) 0.400 atm
D) 0.333 atm
E) 0.500 atm
29) It took 49 sec for 1.0 L of helium to effuse through a pin hole. How long will it take for 1.0 L of
methane, CH4, to effuse under identical conditions?
29)
30) Consider four identical 1.0-L flasks containing the following gases each at 25°C and 1 atm pressure.
For which gas do the molecules have the highest average velocity?
A) NH3
30)
A) 12 s
B) 196 s
C) 7 s
D) 98 s
E) 25 s
B) H2
C) O2
D) SO2
E) same for all gases
31) Consider four identical 1.0-L flasks containing the following gases each at 25°C and 1 atm pressure.
For which gas do the molecules have the greatest average kinetic energy?
A) SO2
31)
B) H2
C) O2
D) NH3
E) same for all gases
32) Equal volumes of an unknown gas and nitrogen (N2 ) gas take 5.37 min and 3.55 minutes,
32)
33) The assumptions of the kinetic-molecular theory are most likely to be correct under what
conditions?
A) low temperature-high pressure
B) high temperature-low pressure
C) high temperature-high pressure
D) low temperature-low pressure
E) always correct
33)
respectively, to effuse through a small hole. Calculate the molar mass (in g/mol) of the unknown
gas.
A) 18.5
B) 64.1
C) 128
D) 12.2
E) 42.4
5
34) Which of the following gases effuses fastest?
A) Cl2
B) F2
C) N2
D) H2
E) O2
34)
35) The greatest deviation of a real gas from the Ideal Gas Law is expected at
A) high T and low P.
B) low T and high P.
C) high T and high P.
D) low T and low P.
E) Real gases don't deviate from the Ideal Gas Law.
35)
36) Which of the following best describes a hot bowl of soup?
A) an open system
B) a closed system
C) system at thermal equilibrium
D) the surroundings
E) an isolated system
36)
37) What is the change in internal energy of a system that has 682 J of work done on it and gives off 485
J of heat?
A) +1167 J
B) +197 J
C) +682 J
D) -197 J
E) -682 J
37)
38) Which is not true for an endothermic reaction?
A) The enthalpy change for the reaction is positive.
B) The temperature of the surroundings decreases.
C) Heat flows from the surroundings into the system.
D) The products have a lower enthalpy than the reactants.
E) All of the above are true.
38)
39) A system absorbs a given quantity of heat and does a given quantity of work. Which of the
following choices correctly indicates the signs for q and w?
A) -q, w
B) q = w = 0
C) -q, -w
D) q, w
E) q, -w
39)
40) Given the following thermochemical equation, calculate the heat (in kJ) involved in decomposing
18.0 g of water to give one mole of H2 (g).
40)
2 H2 (g) + O2 (g)
A) 286
B) 1143
2 H2 O (l)
C) 572
H° = -571.6 kJ
D) -286
E) -572
41) Given the thermochemical equation:
2 NO (g) + O2 (g)
41)
2 NO2 (g)
calculate H° for the following reaction:
NO 2 (g)
A) +114.0 kJ
B) -57.0 kJ
NO( g) +
C) +57.0 kJ
6
H° = -114.0 kJ
1
O (g)
2 2
D) +128 kJ
E) -114 kJ
42) The standard enthalpy change for the following reaction is -72.8 kJ.
H2 (g) + Br2 (l)
42)
2 HBr (g)
What is the standard enthalpy of formation of hydrogen bromide?
A) -72.8 kJ
B) -36.4 kJ
C) -145.6 kJ
D) 72.8 kJ
E) none of the above
43) The extraction of iron from iron ore may be represented by the following equation:
2 Fe2O3 (s) + 3 C (s)
43)
4 Fe (s) + 3 CO2 (g)
Given the information below, calculate H° for the process per mole of Fe2O3.
Hf Fe2 O3 (s) = -826 kJ mol-1
Hf CO2 (g) = -394 kJ mol-1
A) -1220 kJ
B) +235 kJ
C) +470 kJ
D) -470 kJ
E) -2834 kJ
44) Given the following equation,
2 H2 (g) + O2 (g)
44)
2 H2 O (l)
H° = -571.6 kJ/mol,
which statement is incorrect?
A) H° for forming one mole of liquid water is -285.8 kJ/mol.
B) H° for the reverse reaction is +571.6 kJ/mol.
C) H° for the reaction of one-half mole of oxygen is -285.8 kJ/mol.
D) The equation forming gaseous water would have a different H°.
E) The standard heat of formation of liquid water is -571.6 kJ/mol.
45) When 40.0 mL of 0.200 M HCl at 21.5°C is added to 40.0 mL of 0.200 M NaOH also at 21.5°C in a
coffee-cup calorimeter, the temperature of the resulting solution rises to 22.8°C. Assume that the
volumes are additive, the specific heat of the solution is 4.180J g-1 °C-1 , and that the density of the
solution is 1.00 g mL-1. Calculate the enthalpy change, H, for the reaction:
HCl (aq) + NaOH (aq)
A) +435 kJ
B) -435 kJ
NaCl (aq) + H2O (l)
C) +21.5 kJ
7
D) +48.6 kJ
E) -54.3 kJ
45)
46) Given the following equations:
46)
2 H2 (g) + O2 (g)
N2 (g) + O2 (g)
2 H2O (l)
2 NO (g)
N2 (g) + 3 H2 (g)
H = -571.6 kJ
H = +180.5 kJ
2 NH3 (g)
H = -92.22 kJ
Determine the enthalpy change ( H) for the following reaction:
2 NO (g) + 5 H2 (g)
2 NH3 (g) + 2 H2 O (l)
A) -844.3 kJ/mol
B) 844.3 kJ/mol
C) -483.3 kJ/mol
D) -241.7 kJ/mol
E) 483.3 kJ/mol
47) If Hf for O3 (g) is 142.7 kJ mol-1 what is the H° for the following reaction?
3 O2 (g)
47)
2 O3 (g)
A) +285.4 kJ
B) -142.7 kJ
C) +142.7 kJ
D) -285.7 kJ
E) none of the above
48) Which of the following equations correctly describes the reaction illustrating the standard molar
enthalpy of formation for C3 H8O4 (l)?
48)
A) 3 C(graphite) + 4 H2 (g) + 2 O2 (g)
C3H8O4 (l)
C3 H8 O4 (l)
C3 H8 O4 (l)
B) 3 C(graphite) + 8 H (g) + 4 O (g)
C) C3 (s) + H8 (g) + O4 (g)
D) 3 C(graphite) + 4 H2 O (l)
C3H8 O4 (l)
E) 3 CH2 (g) + 2 H+ (aq) + 2 O2 (g)
C3H8O4 (l)
49) Which of the following reactions illustrates the complete combustion of methane (CH4 )?
A) CH4 (g) + S4 (g)
CS2 (g) + 2 H2S (l)
B) 2 CH4 (g) + 3 O2 (g)
2 CO (g) + 4 H2 O (l)
C) CH4 (g) + 2 O2 (g)
D) CH4 (g) + 2 H2O (l)
E) CH4 (g) + Br2 (l)
CO2 (g) + 2 H2O (l)
CO2 (g) + 2 O2 (g)
CH3 Br (l) + HBr (g)
8
49)
50) In the following equation, the enthalpy term can be thought of as part of the reaction. Which of the
following correctly places the enthalpy term into the equation?
H2 + Cl2
2 HCl
H = -185 kJ
A) H2 + 185kJ + Cl2
2 HCl
B) H2 + Cl2
2 HCl + 185kJ
C) H2 + Cl2
2 HCl - 185 kJ
D) 185kJ + H2 + Cl2
2 HCl
E) H2 + Cl2 + 185kJ
2 HCl
9
50)