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Joule expansion. The Joule expansion, in which a volume Vi = V0 is expanded to a volume Vf = 2V0 in a thermally isolated chamber. A free expansion of a gas can be achieved by moving the piston out faster than the fastest molecules in the gas. The Joule expansion (a subset of free expansion) is an irreversible process in thermodynamics in which ...
Joule–Thomson effect. In thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect or Kelvin–Joule effect) describes the temperature change of a real gas or liquid (as differentiated from an ideal gas) when it is expanding; typically caused by the pressure loss from flow through a valve or porous plug while keeping ...
James Prescott Joule FRS FRSE (/ dʒuːl /; [1][2][a] 24 December 1818 – 11 October 1889) was an English physicist, mathematician and brewer, born in Salford, Lancashire. Joule studied the nature of heat, and discovered its relationship to mechanical work. This led to the law of conservation of energy, which in turn led to the development of ...
In chemistry, heat amounts were often measured in calories. Confusingly, there are two common units with that name, respectively denoted cal and Cal: the small calorie (gram-calorie, cal) is 4.184 J exactly. It was originally defined so that the specific heat capacity of liquid water would be 1 cal/(°C⋅g).
In the case of free expansion for an ideal gas, there are no molecular interactions, and the temperature remains constant. For real gasses, the molecules do interact via attraction or repulsion depending on temperature and pressure, and heating or cooling does occur. This is known as the Joule–Thomson effect.
The world's first ice-calorimeter, used in the winter of 1782–83, by Antoine Lavoisier and Pierre-Simon Laplace, to determine the heat involved in various chemical changes; calculations which were based on Joseph Black's prior discovery of latent heat. These experiments mark the foundation of thermochemistry.
The Joule effect (during Joule expansion), the temperature change of a gas (usually cooling) when it is allowed to expand freely. The Joule–Thomson effect, the temperature change of a gas when it is forced through a valve or porous plug while keeping it insulated so that no heat is exchanged with the environment.
Inversion temperature. The inversion temperature in thermodynamics and cryogenics is the critical temperature below which a non- ideal gas (all gases in reality) that is expanding at constant enthalpy will experience a temperature decrease, and above which will experience a temperature increase. This temperature change is known as the Joule ...