8.2 THERMODYNAMICS

• What is the formula for translational kinetic energy?

  $K_{tr} =$$\frac{3}{2} nRT$
• What does Cv equal for translational kinetic energy?

  $C_v =$$\frac{3}{2}$
• What does Cv equal for total kinetic energy of diatomic molecules?

  $C_v =$$\frac{5}{2}$
• How much translational kinetic energy does one mole of O2 have at 127.8°C?

  5.00 x 10³ J
• What is a thermodynamic system?

  • A collection of objects
  • Can exchange energy with the environment
• What causes a change in the state of a thermodynamic system?

  A thermodynamic process
• What are the types of thermodynamic processes?

  1. Isobaric process
  2. Isothermal process
  3. Isochoric process
  4. Adiabatic process
• What characterizes an isobaric process?

  Pressure (p) is kept constant
• What characterizes an isothermal process?

  Temperature (T) is constant
• What characterizes an isochoric process?

  Volume (V) is constant
• What characterizes an adiabatic process?

  No heat (Q) exchange occurs
• What does W (+) represent in thermodynamics?

  Work done by the system
• What does W (-) represent in thermodynamics?

  Work done on the system
• What does Q (+) represent in thermodynamics?

  Heat flow into the system
• What does Q (-) represent in thermodynamics?


  Heat flow out of the system
• What is the sign convention for work done by the system?

  • Work done by the system is negative
  • Piston moves opposite to molecule push
  • Increases kinetic energy
• What is the sign convention for work done on the system?

  • Work done on the system is positive
  • Piston moves in the same direction as molecule push
  • Results in loss of kinetic energy
• What is the formula for work done in a thermodynamic process?

  $dW =$$pA dx =$$p dV$
• What is the work done when pressure is constant?

  $W =$$p (V_f - V_i)$
• What is the work done during an isothermal process?

  $W =$$nRT \ln \frac{V_f}{V_i}$
• How do you calculate work done by an ideal gas during isobaric expansion?

  $W =$$p (V_f - V_i)$
• How do you calculate work done by an ideal gas during isothermal expansion?

  $W =$$nRT \ln \frac{V_f}{V_i}$
• What is the work done by an ideal gas during isobaric expansion from T = 27°C to T = 107°C?

  • Draw a pV-diagram
  • Calculate using $W =$$p (V_f - V_i)$
• What is the work done by an ideal gas during isothermal compression when pressure triples?

  $W =$$-6180 J$
• How does the work done on the gas relate to the final volume in isothermal compression?

  $W =$$nRT \ln \frac{P_1}{P_2}$
• What is the relationship between work done and volume in isothermal compression?

  $W =$$-3nRT$
• What does the First Law of Thermodynamics state?

  • Energy is conserved
  • Energy can be converted but not created or destroyed
  • Total energy in the universe is constant
• Who first stated the law of energy conservation?

  • Robert Mayer
  • German physician
  • Lived from 1814–1878
• What did Mayer observe about the heat produced by animals?

  • Due to slow combustion of food
  • Less food burned in hot environments
• What did Mayer conclude about energy balance in the body?

  Energy released by food balances lost heat
• What did Mayer publish in 1842 regarding energy?

  Energy cannot be annihilated, only changed
• What is the significance of Mayer's observations during his voyage?

  • Verification of Lavoisier's suggestion
  • Connection between energy balance and health
• Who wrote the treatise read aboard the ship?

  Laurent Lavoisier
• What causes heat production in animals?

  Slow combustion of food in their bodies
• How does food burning differ in hot and cold environments?

  Less food is burned in hot environments
• What illness affected the crew when the ship reached the tropics?

  Fever
• What remedy did Mayer apply to his patients with fever?

  He bled his patients
• What change did Mayer observe in venous blood color?

  It was nearly as red as arterial blood
• What did Mayer's observation verify about Lavoisier's suggestion?

  It supported the idea of oxygen content in blood
• Why is venous blood brighter in the tropics?

  High oxygen content due to less fuel burned