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• Thermodynamics


  The branch of physics that deals with relationships between heat, temperature and other forms of energy
• Thermodynamic system


  A specific region of matter or radiation that we're interested in studying within the field of thermodynamics
• Surroundings


  • Everything outside the system is considered the surroundings
  • The system and the surroundings together make up the universe in thermodynamic terms
• Boundaries


  • The imaginary wall that separates the system from the surroundings
  • Can be physical, like the walls of a container, or imaginary, like the boundary around a cloud
• Types of thermodynamic systems

  • Open
  • Closed
  • Isolated
• Open system


  Can exchange both matter and energy with the surroundings
• Closed system


  Can only exchange energy, but not matter, with the surroundings
• Isolated system


  Cannot exchange either matter or energy with the surroundings
• Laws of thermodynamics


  A set of fundamental principles that govern the relationships between heat, work, temperature, and energy transfer in a physical system
• Zeroth law of thermodynamics


  • If two systems are each in thermal equilibrium with a third system, then they are also in thermal equilibrium with each other
  • Allows us to define temperature as a measurable property and to calibrate thermometers
• First law of thermodynamics

  • The total energy of an isolated system remains constant, even though it may change form
  • Energy can neither be created nor destroyed, but it can be transformed from one form to another
• ΔU


  Change in internal energy of the system
• Q


  Heat added to the system from the surroundings
• W


  Work done by the system on the surroundings
• Second law of thermodynamics

  • The entropy of an isolated system always increases over time
  • Explains why some processes are irreversible, such as the flow of heat from a hot object to a cold object
• Third law of thermodynamics

  • The entropy of a system approaches a constant value as the temperature approaches absolute zero
  • A system at absolute zero (0 Kelvin) has perfect order and minimal thermal energy, and therefore has zero entropy
• Thermodynamic process


  The change in the state of a thermodynamic system
• Key types of thermodynamic processes

  • Isothermal
  • Adiabatic
  • Isobaric
  • Isochoric
  • Cyclic
• Isothermal process


  The temperature of the system remains constant
• Adiabatic process


  Occurs with no heat transfer between the system and the surroundings
• Isobaric process


  The pressure of the system remains constant
• Isochoric process


  The volume of the system remains constant
• Cyclic process


  A system goes through a series of changes and returns to its original state
• Work (W)


  The transfer of energy due to a force acting through a distance
• Heat (Q)


  The transfer of thermal energy between a system and its surroundings
• Enthalpy (H)


  A thermodynamic property that represents the total energy of a system at constant pressure
• Internal energy (U)


  The total energy contained within a system, excluding kinetic and potential energy
• Entropy (S)


  A measure of the randomness or disorder of a system
• Specific heat (c)


  A material property that tells you how much heat energy is required to raise the temperature of a unit mass of that substance by one unit of temperature
• Specific heat


  • Quantifies heat transfer
  • Has units of J/kg·K or cal/g·°C
  • Can vary slightly with temperature but is often treated as a constant
• Applications of specific heat

  • Calculating heat transfer
  • Understanding heat capacity
  • Material selection
• Kinetic molecular theory (KMT)


  A model used to describe the behavior of gasses at the microscopic level
• Key principles of KMT

  • Gasses consist of tiny particles
  • Constant random motion
  • Elastic collisions
  • Negligible attractive forces
  • Temperature and kinetic energy
• Boyle's Law


  Compressing a gas at constant temperature increases pressure due to more frequent particle collisions with container walls
• Charles' Law


  Heating a gas increases average particle kinetic energy and speed, resulting in more frequent and forceful collisions with container walls, increasing pressure at constant volume
• The KMT is a simplified model that has limitations in explaining all gas behavior
• Gases


  Can expand to fill their container and easily flow
• Temperature and kinetic energy

  • The average kinetic energy of gas particles is directly proportional to the absolute temperature of the gas
  • Higher temperatures correspond to faster moving particles
• How KMT explains gas laws

  Provides a microscopic explanation for the macroscopic behavior of gases described by gas laws like Boyle's Law, Charles' Law, and the Ideal Gas Law
• Boyle's Law


  • If you compress a gas (decrease its volume) at constant temperature, the gas particles will collide with the container walls more frequently, leading to an increase in pressure