B.4- Thermodynamics

• What is a system in thermodynamics?

  A system is the body or bodies considered that interact with surroundings through energy transfer.
• What are the surroundings in thermodynamics?

  The surroundings are everything else outside the system.
• What are the three types of thermodynamic systems?

  • Open: exchanges thermal energy, work, and matter with surroundings.
  • Closed: exchanges thermal energy and work but not matter.
  • Isolated: cannot exchange thermal energy, work, or matter.
• What is the internal energy of a monoatomic ideal gas?

  The internal energy is the sum of the random kinetic energy of all the particles.
• What does negative work on a gas indicate?

  It indicates that work is done on the gas and it is being compressed.
• What is the formula for work done in gases?

  
  

  W = P x del. V
• What does positive work by a gas indicate?

  It indicates that the gas is doing work and expanding.
• What is the first law of thermodynamics?

  The thermal energy entering a closed system is equal to the sum of the change in internal energy of the system and the work done by the system

  
  

  $Q =$$\Delta U +$$W$
• What happens to internal energy when energy is transferred from surroundings to the system?

  The internal energy increases.
• What is the effect of work done by the system on its internal energy?

  The internal energy decreases.
• What are the 4 types of change?

  1. Isobaric- constant pressure
  2. Isovolumetric- constant volume
  3. Isothermal- constant temperature
  4. Adiabatic- no energy to or from
• What are the equations in the 4 types of change?

  1. Isobaric- Q = del. U + W
  2. Isovolumetric- Q = del. U
  3. Isothermal- Q = W
  4. Adiabatic- del. U = -W
• What is the equation $PV^\gamma =$$\text{constant}$ used for?


  Adiabatic process
• What is the power in the adiabatic equation (PV) for a monoatomic ideal gas?

  5 / 3
• What are the steps of a simple heat engine cycle?

  1. Extract heat from a hot reservoir
  2. Use some heat to perform work
  3. Release excess heat into a cold reservoir
  4. Repeat the cycle
• What is the Carnot cycle?

  The Carnot cycle is an ideal reversible cycle involving isothermal and adiabatic processes with the maximum efficiency of any heat engine
• What is the second law of thermodynamics?

  It considers the direction in which energy transfer can occur.
• What does the Clausius version of the second law state?

  Energy cannot be transferred from a lower temperature body to a higher temperature body without work done on the system.
• What does the Kelvin and Planck version of the second law state?

  Energy cannot be extracted from a hot object and transformed entirely into work.
• What is entropy?

  Entropy is a measure of the number of possible arrangements of particles and their energies.
• How does entropy change from solid to gas?

  Entropy increases as the state changes from solid to gas.
• What is a microstate?

  A microstate is a specific molecular configuration of a system.
• What is a macrostate?

  A macrostate is a larger-scale, measurable outcome resulting from the combination of microstates.
• How does the second law of thermodynamics relate to entropy?

  The second law states that the total entropy of an isolated system can never decrease over time.
• What is the relationship between temperature and entropy as energy increases?

  As energy increases, temperature also increases, leading to higher entropy.
• How does the concept of microstates relate to entropy?

  Entropy is a measure of the number of possible microstates of a system.
• What is the area inside the thermodynamic processes graph?

  Output energy or net work done
• What is the area below a thermodynamic processes graph?

  Input energy
• What is a heat engine?

  It converts thermal energy into mechanical work
• How does a heat engine work?

  1. Energy is transferred into the engine to create a hot reservoir
  2. Some energy is used as work to expand the piston
  3. Gas cools and energy is released into a cold reservoir
  4. The piston compresses
  5. The difference between the two energies is used for work
• How does the Carnot cycle work?

  1. Isothermal expansion- energy into gas at a high temperature
  2. Adiabatic expansion- internal energy and temp. falls
  3. Isothermal compression- energy is lost to surroundings at constant temp.
  4. Adiabatic compression- internal energy and temp. rises
• How do refrigerators and heat pumps compare to heat engines?

  They are the opposite
• How does a refrigerator work?

  1. Compression- inputs work, mostly liquid
  2. Back of fridge- loses heat, all liquid
  3. Expansion valve- loses temp and pressure, gas and liquid
  4. Inside- extracts heat, mostly gas