Transcript Exam 4-6 Practice

Chemistry 107
Exam 4-6
Good Luck!
1. The overall equation involved in photosynthesis is:
6 CO2 + 6 H2O  C6H12O6 + 6 O2
How many grams of glucose (C6H12O6) form when 4.40 g of
CO2 react?
a) 18.0 g
b) 3.00 g
c) 108 g
d) 0.0167 g
2. The rapid decomposition of sodium azide, NaN3, to its
elements is one of the reactions used to inflate airbags:
2 NaN3 (s)  2 Na (s) + 3 N2 (g)
How many grams of N2 are produced from 6.00 g of NaN3
a) 3.88 g
b) 1.72 g
c)0.138 g
d) 2.59 g
N2
3. Ammonia is produced using the Haber process:
3 H2 + N2  2 NH3
What percent yield of ammonia produced from 15.0 kg each
of H2 and N2, if 13.7 kg of product are recovered? Assume
the reaction goes to completion.
a) 7.53 x 10-2 %
b) 1.50 x 10-1 %
c) 75.3%
d) 15.0%
e) 16.2%
4. Ammonia is produced using the Haber process:
3 H2 + N2  2 NH3
Calculate the mass of ammonia produced when 35.0 g of
nitrogen react with 12.5 g of hydrogen.
a) 47.5 g
b) 42.6 g
c) 35.0 g
d) 63.8 g
e) 70.5 g
5. What mass, in grams, of sodium
bicarbonate, NaHCO3, is required to
neutralize 1000.0 L of 0.350 M H2SO4?
H2SO4 + 2 NaHCO3  2 CO2 + Na2SO4 + 2 H2O
a) 2.94 x 104 g
b) 1.47 x 104 g
c) 5.88 x 104 g
d) 3.50 x 103 g
e) 1.75 x 103 g
6. Aqueous solutions of which of the
following would conduct electricity?
a) AgNO3
b) C11H22O11 (sucrose: table sugar)
c) CH3CH2OH (ethanol)
d) All of the above
e) None of the above
7. Sulfuric acid is found in some types of
batteries. What volume of 3.50 M H2SO4 is
required to prepare 250.0 mL of 1.25 M
H2SO4?
a) 17.5 mL
b) 700. mL
c) 89.3 mL
d) 109 mL
e) None of the
above
8. Determine the oxidation number of the Nitrogen
N2O4
a) + 4
b) - 4
c) + 8
d) - 8
9. The overall equation involved in photosynthesis is:
6 CO2 + 6 H2O  C6H12O6 + 6 O2
How many grams of carbon dioxide (CO2) are required to
produce 18.0 g of C6H12O6?
a) 18.0 g
b) 3.00 g
c) 54.0 g
d) 26.4 g
e) 4.40 g
10. What is the maximum number of grams of PbI2
precipitated upon mixing 25.0 mL of 0.150 M KI
with 15.0 mL of 0.175 M Pb(NO3)2?
Pb(NO3)2 + 2KI  2KNO3 + PbI2
a) 0.864 g
b) 1.73 g
c) 1.21 g
d) 2.07 g
e) None of the
above
11. A 25.0 mL sample of H2SO4 is neutralized with
NaOH. What is the concentration of the H2SO4 if
35.0 mL of 0.150 M NaOH are required to
completely neutralize the acid?
a) 0.210 M
b) 0.105 M
c) 0.150 M
d) 0.420 M
e) None of the
above
2NaOH + H2SO4 
Na2SO4 + 2H2O
12. Which of the following is a
redox reaction?
a) HBr (aq) + KOH (aq) → H2O (l) + KBr (aq)
b) SO3 (g) + H2O (l) → H2SO4 (aq)
c) HBr (aq) + Na2S (aq) → NaBr (aq) + H2S (g)
d) NH4+ (aq) + 2 O2 (g) → H2O (l) + NO3– (aq) + 2 H+ (aq)
e) None of the above
13. What is the reducing agent in the following reaction?
Zn + 2 MnO2 + 2 H2O → Zn(OH)2 + 2 MnO(OH)
a) Zn
b) MnO2
c) H2O
d) Zn(OH)2
e) MnO(OH)
14. What is the molarity of an aqueous solution
containing 22.5 g of sucrose (C12H22O11) in 35.5
mL of solution?
a) 0.0657 M
b) 1.85 x 10-3 M
c) 1.85 M
d) 3.52 M
e) 0.104 M
15. Which of the following compounds will be
insoluble in water?
a) Ca(OH)2
b) Na3PO4
c) CaS
d) Hg2Cl2
e) LiF
16. How many moles of helium are
found in a balloon that contains 5.5
L of helium at a pressure of 1.15
atm and a temperature of 22.0 ºC?
a) 3.5
b) 0.26
c) 2.6
d) 0.35
e) 3.8
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17. The four most common gases in the
atmosphere are N2, O2, Ar, and CO2. Which
gas has the highest average kinetic energy
at room temperature?
a) N2
b) O2
c) Ar
d) CO2
e) All have the same
average kinetic
energy
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18. The four most common gases in the
atmosphere are N2, O2, Ar, and CO2. Assuming all
gases are in containers of equal size, temperature,
and pressure, which gas has the highest density?
a) All have the same
density
b) N2
c) O2
d) Ar
e) CO2
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19. Under what conditions would
Cl2 gas be the least ideal?
a) High pressure and low
temperature
b) High pressure and high
temperature
c) Low pressure and high
temperature
d) Low pressure and low
temperature
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20. The volume of O2 gas in a balloon at 1.0 atm
and 305 K is 0.65 L. Calculate the volume of the
gas after the temperature is lowered to 77 K while
keeping the pressure and amount of O2 constant.
a) 0.16 L
b) 0.65 L
c) 2.8 x 10–5 L
d) 3.6 x 104 L
e) Not enough
information
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21. Which of the following will have the
greatest volume at STP?
a) 5.0 g H2
b) 5.0 g N2
c) 5.0 g O2
d) 5.0 g CO
e) All of the above
have the same
volume.
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22. A 3.50 g sample of a diatomic gas in a
1.5 L container has a pressure of 2.42 atm
at 355 K. Determine the identity of the gas.
a) H2
b) N2
c) Cl2
d) O2
e) F2
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23. A gas phase mixture of H2 and N2 has a total
pressure of 784 torr with an H2 partial pressure of 124
torr. What mass of N2 gas is present in 2.00 L of the
mixture at 298 K?
a) 0.0133 g
b) 0.0710 g
c) 0.374 g
d) 0.994 g
e) 1.99 g
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24. What mass of water vapor is produced from the gas phase
reaction of O2 with H2 in a 2.5 L container at 28 °C if the partial
pressures of O2 and H2 are PO = 0.98 atm and PH = 1.24 atm
2
2
2 H2 (g)+ O2 (g)→ 2 H2O (g)
a) 1.79 g
b) 2.25 g
c) 3.57 g
d) 4.51 g
e) 5.82 g
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25. Calculate the internal energy, ΔE, for a system
that does 422 J of work and loses 227 J of energy
as heat.
a) + 649 J
b) – 649 J
c) 0 J
d) – 195 J
e) + 195 J
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26. A 3.54 g piece of aluminum is heated to 96.2 ºC and
allowed to cool to room temperature, 22.5 ºC. Calculate the
heat (in kJ) associated with the cooling process. The specific
heat of aluminum is 0.903 J/ g · K
a)
b)
c)
d)
e)
+ 0.236
– 236
+ 236
– 0.236
– 0.638
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27. The main engines of the Space Shuttle burn hydrogen to
produce water. How much heat (in kJ) is associated with this
process if 1.32 x 105 kg of liquid H2 is burned?
2 H2 (l ) + O2 (l ) → 2 H2O (l )
a) – 571.6
b) – 285.8
c) – 1.87 x 1010
d) – 3.74 x 1010
e) – 7.55 x 107
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ΔHºrxn = – 571.6 kJ
28. A 32.5-g cube of aluminum initially at 45.8 °C is
submerged into 105.3 g of water at 15.4 °C. What is the
final temperature of both substances at thermal
equilibrium? The specific heat capacity of aluminum =
0.903 J/ g °C; of water = 4.18 J/ g °C
a) -17.3
b) 17.3
c) –25.2
d) 39.2
e) – 39.2
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29. Which of the following has a negative
value of ΔH?
a) the combustion of gasoline
b) the melting of snow
c) the evaporation of ethanol
d) the sublimation of CO2 at room temperature
e) All of the above have positive ΔH values.
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30. Which of the following statements about
enthalpy is false?
a) The value of ΔH for a chemical reaction is the amount of
heat absorbed or evolved in the reaction under
conditions of constant pressure.
b) An endothermic reaction has a positive ΔH and absorbs
heat from the surroundings. An endothermic reaction
feels cold to the touch.
c) An exothermic reaction has a negative ΔH and gives off
heat to the surroundings. An exothermic reaction feels
warm to the touch.
d) Statements (a), (b), and (c) are all false statements.
e) Statements (a), (b), and (c) are all true statements.
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31. Use Hess’s Law, determine ΔH for the target reaction below.
½ N2 (g) + ½ O2 (g) → NO (g)
NO (g) + ½ Cl2 (g) → NOCl (g)
ΔH = 90.3 kJ
ΔH = –38.6 kJ
2 NOCl (g) → N2 (g) + O2 (g) + Cl2 (g) ΔH = ?
a) –51.7 kJ
b) 51.7 kJ
c) –103.4
kJ
d) 103.4 kJ
e) 142.0 kJ
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The Answers
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1. B
2. A
3. C
4. B
5. C
6. A
7. C
8. A
9. D
10. A
11. B For Fun Not on Test
12. D
13. A
14. C
15. D
16. B
17. E
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18. E
19. B
20. A
21. A
22. B
23. E
24. B
25. B
26. D
27. C
28. B
29. A
30. E
31. C