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First Law of Thermodynamics definitions

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  • First Law of Thermodynamics
    Energy cannot be created or destroyed, only transferred between a system and its surroundings.
  • System
    The substance or chemical reaction under study in thermodynamics.
  • Surroundings
    Everything outside the system, including the container and the universe.
  • Energy Transfer
    The movement of energy in the form of heat or work between a system and its surroundings.
  • Heat
    The flow of thermal energy from a higher temperature object to a lower temperature object.
  • Work
    The movement of reacting molecules against gravity or an opposing force.
  • Q
    The variable representing heat in thermodynamics, positive when gained, negative when lost.
  • W
    The variable representing work, negative when the system does work, positive when work is done on it.
  • Thermal Energy
    Energy in the form of heat that moves from hotter to colder objects.
  • Piston
    A component that can move up or down, used to demonstrate work in thermodynamics.
  • Negative Q
    Indicates the system is losing heat to the surroundings.
  • Positive Q
    Indicates the system is gaining heat from the surroundings.
  • Negative W
    Indicates the system is doing work on the surroundings.
  • Positive W
    Indicates the surroundings are doing work on the system.