Worksheet: Heat and Work

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

Q1:

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.

Q2:

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.

Q3:

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

Q4:

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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