Chapter 18: Answers to Stop to Think Questions and Odd-Numbered Exercises and Problems

Stop to Think Questions

  1. 1. d. The pressure decreases by 20 kPa.

  2. 2. a. The number of atoms depends only on the number of moles, not the substance.

  3. 3. a. The step size on the Kelvin scale is the same as the step size on the Celsius scale. A change of 10°C is a change of 10 K.

  4. 4. Increase. When an object undergoes thermal expansion, all dimensions increase by the same percentage.

  5. 5. a. On the water phase diagram, you can see that for a pressure just slightly below the triple-point pressure, the solid/gas transition occurs at a higher temperature than does the solid/liquid transition at high pressures. This is not true for carbon dioxide.

  6. 6. c. T=pV/nR. Pressure and volume are the same, but n differs. The number of moles in mass M is M=M/Mmol. Helium, with the smaller molar mass, has a larger number of moles and thus a lower temperature.

  7. 7. b. The pressure is determined entirely by the weight of the piston pressing down. Changing the temperature changes the volume of the gas, but not its pressure.

  8. 8. b. The temperature decreases by a factor of 4 during the isochoric process, where pf/pi=14. The temperature then increases by a factor of 2 during the isobaric expansion, where Vf/Vi=2.

Exercises and Problems

  1. 1. 1900 cm3

  2. 3. 8.0 cm

  3. 5. 4.8×1023 atoms

  4. 7. 24

  5. 9. 1.5 cm

  6. 11. −40°

  7. 13.

    1. 171°Z

    2. 671°C=944 K

  8. 15. 0.059 mm

  9. 17. 12 mm

  10. 19. 19 atm

  11. 21.

    1. 1.27V0

    2. 2V0

  12. 23. 2.5×1024 molecules

  13. 25.

    1. 1.6 mol

    2. 9.4×1023 molecules

    3. 7.5×1025 m−3

    4. 200 kPa

  14. 27.

    1. V2=V1

    2. T13

  15. 29. 2.6 atm

  16. 31.

    1. 105,600 Pa

    2. 42 cm

  17. 33.

    1. 48 atm

  18. 35.

    1. Isobaric

    2. 3200°C

    3. 4.1×10−3 mol

  19. 37.

    1. −29°C

    2. 4.0 atm

    3. 500 cm3

  20. 39.

    The figure illustrates the pressure versus volume graph of a thermodynamic cycle.

  21. 41. 3.3×1026 protons

  22. 43. 333°C

  23. 45. 107°C

  24. 47. 17.2 m

  25. 49. 2.4 m

  26. 51.

    1. 82 L

    2. 79 m3

  27. 53. 29 cm

  28. 55. 9.8×102 m3

  29. 57.

    1. 23 cm

    2. 7.5 cm

  30. 59. 1.8 cm

  31. 61.

    1. 889 kPa

    2. 323°C, −49°C, 398°C

  32. 63. −152°C

  33. 65.

  34. 67.

  35. 69.

  36. 71. 5.06 kN

  37. 73. 1.0 cm