Chemistry 107 Exam 4-6 Good Luck!. a) 18.0 g b) 3.00 g c) 108 g d) 0.0167 g 1. The overall equation...

Chemistry 107

Exam 4-6

Good Luck!

a) 18.0 g

b) 3.00 g

c) 108 g

d) 0.0167 g

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) 3.88 g

b) 1.72 g

c)0.138 g

d) 2.59 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

N2

a) 7.53 x 10-2 %

b) 1.50 x 10-1 %

c) 75.3%

d) 15.0%

e) 16.2%

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) 47.5 g

b) 42.6 g

c) 35.0 g

d) 63.8 g

e) 70.5 g

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.

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

N2O4

a) + 4

b) - 4

c) + 8

d) - 8

8. Determine the oxidation number of the Nitrogen

a) 18.0 g

b) 3.00 g

c) 54.0 g

d) 26.4 g

e) 4.40 g

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?

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) Hg2Cl2e) 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) Cl2d) 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

2 = 0.98 atm and PH

2 = 1.24 atm

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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a) + 649 J

b) – 649 J

c) 0 J

d) – 195 J

e) + 195 J

25. Calculate the internal energy, ΔE, for a system that does 422 J of work and loses 227 J of energy as heat.

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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) + 0.236

b) – 236

c) + 236

d) – 0.236

e) – 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 ) ΔHºrxn = – 571.6 kJ

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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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) ΔH = 90.3 kJNO (g) + ½ Cl2 (g) → NOCl (g) 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• 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

• 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