Assignment: Thermodynamics

Instructions

As you work these matter and measurement problems, consider and explain:

  1. What type of question is it?
  2. How do you know what type of question it is?
  3. What information are you looking for?
  4. What information do they give?
  5. How will you go about solving this?
  6. Show how to solve the problem.
  7. Be able to answer for a different reaction, number, set of conditions, etc.


Questions

  1. A gas absorbs 0.0 J of heat and then performs 31.7 J of work. What is the change in internal energy of the gas?

    1. 63.4 J
    2. 31.7 J
    3. –63.4 J
    4. –31.7
    5. none of these


  2. Which of the following statements correctly describes the signs of q and w for the following exothermic process at P = 1 atm and T = 370 K? H2O(g) → H2O(l)

    1. q and w are negative
    2. q is positive, w is negative
    3. q is negative, w is positive
    4. q and w are both positive
    5. q and w are both zero


  3. Which of the following statements is correct?

    1. The internal energy of a system increases when more work is done by the system than heat was flowing into the system.
    2. The internal energy of a system decreases when work is done on the system and heat is flowing into the system.
    3. The system does work on the surroundings when an ideal gas expands against a constant external pressure.
    4. All statements are true.
    5. All statements are false.


  4. One mole of an ideal gas is expanded from a volume of 1.00 liter to a volume of 3.10 liters against a constant external pressure of 1.00 atm. How much work (in joules) is performed on the surroundings? Ignore significant figures for this problem. (T = 300 K; 1 L·atm = 101.3 J)

    1. 106 J
    2. 213 J
    3. 6.38 × 102 J
    4. 314 J
    5. none of these


  5. A fuel-air mixture is placed in a cylinder fitted with a piston. The original volume is 0.285-L. When the mixture is ignited, gases are produced and 805 J of energy is released. To what volume will the gases expand against a constant pressure of 635 mmHg, if all the energy released is converted to work to push the piston?

    1. 9.22 L
    2. 6.92 L
    3. 9.79 L
    4. 9.51 L
    5. 1.55 L




Use the following to answer questions 1 and 2:

Consider a gas in a 1.0 L bulb at STP that is connected via a valve to another bulb that is initially evacuated. Answer the following concerning what occurs when the valve between the two bulbs is opened.

  1. What is true about the value of w?

    1. It is greater than zero.
    2. It is equal to zero.
    3. It is less than zero.
    4. More information is needed.
    5. None of these.


  2. What is true about the value of ΔH?

    1. It is greater than zero.
    2. It is equal to zero.
    3. It is less than zero.
    4. More information is needed.
    5. None of these.




Answer the following questions:

  1. Which of the following properties is (are) intensive properties?

    1. mass
    2. temperature
    3. volume
    4. concentration
    5. energy


    1. I, III, and V
    2. II only
    3. II and IV
    4. III and IV
    5. I and V


  2. Which one of the following statements is false?

    1. The change in internal energy, ΔE, for a process is equal to the amount of heat absorbed at constant volume, qv.
    2. The change in enthalpy, ΔH, for a process is equal to the amount of heat absorbed at constant pressure, qp.
    3. A bomb calorimeter measures ΔH directly.
    4. If qp for a process is negative, the process is exothermic.
    5. The freezing of water is an example of an exothermic reaction.


  3. Consider this reaction: C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l); Δ H = –1.37 × 103 kJ

    Consider the following propositions:

    1. The reaction is endothermic
    2. The reaction is exothermic.
    3. The enthalpy term would be different if the water formed was gaseous.
    4. Which of these propositions is (are) true?


    1. I
    2. II
    3. III
    4. I, II
    5. II, III


  4. Two metals of equal mass with different heat capacities are subjected to the same amount of heat. Which undergoes the smallest change in temperature?

    1. The metal with the higher heat capacity.
    2. The metal with the lower heat capacity.
    3. Both undergo the same change in temperature.
    4. You need to know the initial temperatures of the metals.
    5. You need to know which metals you have.


  5. A 48.2 g sample of a metal is heated to 97.5°C and then placed in a calorimeter containing 120.0 g of water (c = 4.18 J/g°C) at 21.3°C. The final temperature of the water is 24.5°C. Which metal was used?

    1. Aluminum (c = 0.89 J/g°C)
    2. Iron (c = 0.45 J/g°C)
    3. Copper (c = 0.20 J/g°C)
    4. Lead (c = 0.14 J/g°C)
    5. none of these


  6. The enthalpy of fusion of ice is 6.020 kJ/mol. The heat capacity of liquid water is 75.4 J/mol·°C. What is the smallest number of ice cubes at 0°C, each containing one mole of water, necessary to cool 500 g of liquid water initially at 20°C to 0°C?

    1. 1
    2. 7
    3. 14
    4. 15
    5. 126


  7. Consider the reaction H2(g) + O2(g) → H2O(l) ΔH° = –286 kJ

    Which of the following is true?

    1. The reaction is exothermic.
    2. The reaction is endothermic.
    3. The enthalpy of the products is less than that of the reactants.
    4. Heat is absorbed by the system.
    5. Both A and C are true.


  8. If 5.0 kJ of energy is added to a 15.5-g sample of water at 10°C, the water is _______.

    1. boiling
    2. completely vaporized
    3. frozen solid
    4. decomposed
    5. still a liquid


  9. A chunk of lead at 91.3°C was added to 200.0 g of water at 15.5°C. The specific heat of lead is 0.129 J/g°C, and the specific heat of water is 4.18 J/g°C. When the temperature stabilized, the temperature of the mixture was 20.5°C. Assuming no heat was lost to the surroundings, what was the mass of lead added?

    1. 1.88 kg
    2. 355 g
    3. 427 g
    4. 458 g
    5. none of these


  10. What is the specific heat capacity of graphite if it requires 266 J to raise the temperature of 15 grams of graphite by 25°C?

    1. 1.4 J/g°C
    2. 0.71 J/g°C
    3. 0.43 J/g°C
    4. 0.60 J/g°C
    5. none of these


  11. Consider this reaction: When a 11.6-g sample of ethyl alcohol (molar mass = 46.07 g/mol) is burned, how much energy is released as heat?

    1. 0.252 kJ
    2. 0.345 kJ
    3. 3.45 × 102 kJ
    4. 1.59 × 104 kJ
    5. 3.97 kJ


  12. Given the equation S(s) + O2(g) → SO2(g), ΔH = –296 kJ, which of the following statement(s) is (are) true?

    1. The reaction is exothermic.
    2. When 0.500 mole sulfur is reacted, 148 kJ of energy is released.
    3. When 32.0 g of sulfur are burned, 2.96 × 105 J of energy is released.


    1. All are true.
    2. None is true.
    3. I and II are true.
    4. I and III are true.
    5. Only II is true.


  13. Consider the following specific heats of metals.

    Metal Specific Heat
    Zinc 0.387 J/(g°C
    Magnesium 1.02 J/(g°C
    Mercury 0.138 J/(g°C
    Silver 0.237 J/(g°C
    Bismuth 0.123 J/(g°C
    If the same amount of heat is added to 25.0 g of each of the metals, which are all at the same initial temperature, which metal will have the highest temperature?

    1. Zinc
    2. Magnesium
    3. Mercury
    4. Silver
    5. Bismuth


  14. The specific heat capacities of metals are relatively low.

    1. True
    2. False


  15. At 25°C, the following heats of reaction are known:

    ΔH (kJ/mol)
    2ClF + O2 → Cl2O + F2O 167.4
    2ClF + O2 → Cl2O + F2O 341.4
    2F2 + O2 → 2F2O –43.4
    At the same temperature, calculate ΔH for the reaction: ClF + F2 → ClF3

    1. –217.5 kJ/mol
    2. –130.2 kJ/mol
    3. +217.5 kJ/mol
    4. –108.7 kJ/mol
    5. none of these


  16. Given the heats of the following reactions:

    ΔH°(kJ)
    I. P4(s) + 6Cl2(g) → 4PCl3(g) –1225.6
    II. P4(s) + 5O2(g) → P4O10(s) –2967.3
    III. PCl3(g) + Cl2(g) → PCl5(g) –84.2
    IV. PCl3(g) + O2(g) → Cl3PO(g) –285.7
    Calculate the value of ΔH° for the reaction below:

    P4O10(s) + 6PCl5(g)

    1. –110.5 kJ
    2. –610.1 kJ
    3. –2682.2 kJ
    4. –7555.0 kJ
    5. None of these is within 5% of the correct answer.


  17. Using the following thermochemical data, calculate ΔHf° of Er2O3(s).

    2ErCl3(s) + 3H2O(l) → Er2O3(s) + 6HCl(g) H° = 403.1 kJ/mol
    2Er(s) + 3Cl2(g) → 2ErCl3(s) H° = –1997.4 kJ/mol
    4HCl(g) + O2(g) → 2Cl2(g) + 2H2O(l) H° = –202.4 kJ/mol
    1. –1897.9 kJ/mol
    2. –1796.7 kJ/mol
    3. 2602.9 kJ/mol
    4. –2198.1 kJ/mol
    5. 1391.9 kJ/mol


  18. Given the following:

    Cu2O(s) + O2(g) → 2CuO(s) ΔH° = –144 kJ
    Cu2O(s) → Cu(s) + CuO(s) ΔH° = +11 kJ
    Calculate the standard enthalpy of formation of CuO(s).

    1. –166 kJ
    2. –299 kJ
    3. +299 kJ
    4. +155 kJ
    5. –155 kJ


  19. The heat combustion of acetylene, C2H2(g), at 25°C is –1299 kJ/mol. At this temperature, ΔHf° values for CO2(g) and H2O(l) are –393 and –286 kJ/mol, respectively. Calculate ΔHf° for acetylene.

    1. 2376 kJ/mol
    2. 625 kJ/mol
    3. 227 kJ/mol
    4. –625 kJ/mol
    5. –227 kJ/mol


  20. For the reaction:

    AgI(s) + Br2(g) → AgBr(s) + I2(s), ΔH°= –54.0 kJ

    ΔHf° for AgBr(s) = –100.4 kJ/mol

    ΔHf° for Br2(g) = +30.9 kJ/mol

    What is the value of ΔHf° for AgI(s)?

    1. –123.5 kJ/mol
    2. +77.3 kJ/mol
    3. +61.8 kJ/mol
    4. –77.3 kJ/mol
    5. –61.8 kJ/mol


  21. For which of the following reaction(s) is the enthalpy change for the reaction not equal to ΔHf° of the product?

    1. 2H(g) → H2(g)
    2. H2(g) + O2(g) → H2O2(l)
    3. H2O(l) + O(g) → H2O2(l)


    1. I
    2. II
    3. III
    4. I and III
    5. II and III


  22. The following statements concerning petroleum are all true except:

    1. It is a thick, dark liquid composed mostly of hydrocarbons.
    2. It must be separated into fractions (by boiling) in order to be used efficiently.
    3. Some of the commercial uses of petroleum fractions include gasoline and kerosene.
    4. It was probably formed from the remains of ancient marine organisms.
    5. All of its hydrocarbon chains contain the same number of carbon atoms.


  23. What is the coal with the highest energy available per unit burned?

    1. Lignite
    2. Subbituminous
    3. Bituminous
    4. Anthracite
    5. They are equal in energy value.


  24. Which of the following is both a greenhouse gas and a fuel?

    1. carbon dioxide
    2. coal
    3. freon
    4. methane
    5. nitrogen


  25. Which of the following is not being considered as an energy source for the future?

    1. ethanol
    2. methanol
    3. seed oil
    4. shale oil
    5. carbon dioxide




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