Worksheet: Heat and Work

In this worksheet, we will practice defining work, thermal energy, and heat in the context of chemical and physical changes.


Which of the following is the best definition of heat?

  • AHeat is the temperature of a substance.
  • BHeat is non-work energy transferred from a hot body to a cold body.
  • CHeat is the difference in temperature between a hot and a cold body.
  • DHeat is the thermal energy of a substance.


Which of the following corresponds to a concise statement of the zeroth law of thermodynamics?

  • ATwo material bodies that are separately in thermal equilibrium with a third body are in thermal equilibrium with each other.
  • BGas molecules in motion tend to stay in motion in the absence of applied forces.
  • CThree solid bodies that are all in thermal equilibrium will have the same temperature.
  • DMolecules can be treated as noninteracting point masses when contained in gaseous samples at very low pressures and number densities.


What is the name of the process in which there is no thermal energy exchanged between a system and its surroundings?

  • AIsochoric process
  • BAn adiabatic process
  • CAn isothermal process
  • DA diathermic process
  • EAn isobaric process


Consider a process in which a sample of water vapor expands reversibly and adiabatically from a state in which its pressure is 8.0×10 bar and its volume is 0.5 dm3 to a state in which its volume is 3 dm3. If it is assumed that the water vapor behaves as an ideal gas (with respect to its 𝑃𝑉𝑇 properties) and that the ratio of its 𝐶 and 𝐶 heat-capacity quantities is given by 𝛾=𝐶𝐶=1.3, what will the final pressure of the vapor sample be?

  • A5.83 bar
  • B7.79×10 bar
  • C0.307 bar
  • D0.821 bar

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