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Practice questions

Practice questions. Chapters 19 & 20. Practice questions from chapter 19&20 1. For a particular process, q = 20 kJ and w = 15 kJ. Which of the following statements is true? a) Heat flows from the system to the surroundings. b) The system does work on the surroundings. c) ∆ U = 35 kJ.

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Practice questions

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  1. Practice questions Chapters 19 & 20

  2. Practice questions from chapter 19&20 • 1. For a particular process, q = 20 kJ and w = 15 kJ. Which of the following statements is true? • a) Heat flows from the system to the surroundings. • b) The system does work on the surroundings. • c) ∆U = 35 kJ. • d) All of the above are true. • e) None of the above are true. • 2. Which of the following compounds has the highest standard entropy per mole at 298 K? • a) CH3OH(l) • b) CO(g) • c) SiO2(s) • d) H2O(l) • e) CaCO3(s)

  3. 3.The total entropy of a system and its surroundings always increases for a spontaneous process. This is a statement of • a) the law of constant composition. • b) the first law of thermodynamics. • c) the second law of thermodynamics. • d) the third law of thermodynamics. • e) the law of conservation of matter. • 4. The standard enthalpy of vaporization of Freon-10, CCl4, is 29.82 kJ/mol at its normal boiling point of 77°C. What is the change of entropy for 1 mol of liquid Freon-10 when it vaporizes at its normal boiling point? • a) 85.2 J/K • b) 0.387 J/K • c) 3.87 × 102 J/K • d) 8.52 × 10–2 J/K • e) 1.04 × 104 J/K

  4. 5. The standard enthalpy of vaporization of chloroform is 29.2 kJ/mol at its normal boiling point, 61.2°C. What is the standard change in entropy for the vaporization of chloroform at its normal boiling point? • a) –29.2 J/(mol · K) • b) 0.477 J/(mol · K) • c) 477 J/(mol · K) • d) 87.3 J/(mol · K) • 0.0873 J/(mol · K) • 6. At the normal boiling point of o-xylene, ∆H°vap = 36.2 kJ/mol and ∆S°vap = 86.7 J/(mol · K). What is the normal boiling point of o-xylene? • a) 418 K • b) 115 K • c) 867 K • d) 314 K • e) 373 K

  5. 7. Which of the following equations is correct? • a) G = S – TH • b) ∆G = Ginitial – Gfinal • c) G = H – TS • d) G = S – PV • e) G = H – PV • 8. What is ∆G° at 298 K for the following reaction? • I2(g) + Cl2(g) → 2ICl(g); ∆H° = –27.4 kJ; ∆S° = 11.5 J/K at 298 K • a) –24.0 kJ • b) –3.45 × 103 kJ • c) –30.8 kJ • d) 3.45 × 103 kJ • e) 30.8 kJ

  6. 9. For a certain process, at 300. K, ∆G = –20.0 kJ and ∆H = –7.0 kJ. If the process is carried out reversibly, what is the amount of useful work that can be performed? • a) –27.0 kJ • b) –7.0 kJ • c) –13.0 kJ • d) –20.0 kJ • e) 13.0 kJ • 10. Consder the following reaction: • 3C(s) + 4H2(g) → C3H8(g); ∆H° = –104.7 kJ; ∆S° = –287.4 J/K at 298 K • What is the equilibrium constant at 400.0 K for this reaction? • a) 1.0 • b) 3.1 × 102 • c) 2.2 × 101 • d) 4.6 × 10–2 • e) 1.0 × 10–15

  7. 13. According to the following cell notation, which species is undergoing oxidation? • Cu | Cu2+(aq) || Mn2+(aq) | MnO2(s) | Pt • a) Cu • b) Cu2+ • c) Pt • d) MnO2 • e) Mn2+ • 14. What is the cell reaction for the following electrochemical cell? • Mg | Mg2+(aq) || Zn2+(aq) | Zn • a) Mg(s) + Mg2+(aq) → Zn(s) + Zn2+(aq) • b) Mg(s) + Zn2+(aq) → Zn(s) + Mg2+(aq) • c) 2Zn(s) + Mg2+(aq) → Mg(s) + 2Zn2+(aq) • d) 2Mg(s) + Zn2+(aq) → Zn(s) + 2Mg2+(aq) • e) Zn(s) + Mg2+(aq) → Mg(s) + Zn2+(aq)

  8. 16. Which of the following is not part of a voltaic cell? • a) salt bridge • b) power strip • c) anode • d) cathode • e) external circuit

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