The First Law of Thermodynamics W1.1

• First Law of Thermodynamics

  • Energy can be neither be created nor destroyed. It can only be transferred between systems and the surroundings.
  • The change in the internal energy of a system is equal to the amount of heat supplied to the system minus the amount of work done on its surroundings.
• Work (w) - transfer of mechanical energy from one object to another due to displacement or force
• Heat (q) - transfer of thermal energy from one object to another due to temperature difference
• Internal Energy (U) - sum total of all energies within a substance
• Isovolumetric process

  • refers to a process when there is no change in volume for the system, that means that no pressure-volume work can be done on or by the system, so work is zero in such case.
  • An example of this is the bomb calorimeter, wherein combustion occurs in a rigid container such that only heat transfer occurs
  • Any change in energy is the result of heat transfer.
• Isothermal process

  • Heat transferred is completely used for work (Q = W)
  • A perfect car engine would use all of its energy (heat) for work.
• Adiabatic process

  • Occurs when there is no heat transfer, and that the internal energy of a system changes as a result and vice versa.
  • The Earths' natural processes can set an example for this process.
• Isolated system

  • Occurs when there is no heat and work transfer, and there is no change in the internal energy.