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B Free expansion of gas

  1. Nov 7, 2018 #1
    If a gas is suddenly allowed to expand freely and adibatically inside a container then from the first law of thermodynamics dQ=0,
    My question is whether the change of internal energy would be 0 and if it then how would the work done be 0 (since accessible volume of the gas changes inside the container changes)??
  2. jcsd
  3. Nov 7, 2018 #2

    Lord Jestocost

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  4. Nov 7, 2018 #3
  5. Nov 7, 2018 #4


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    For a real gas, you have to take into account the interaction between particles. In most cases, there is an overall attractive interaction (negative potential energy) which leads to a decrease in temperature when the gas expands and the attraction between the particle is globally lower because of the greater volume occupied. Note that this is not always true, as each gas has an inversion temperature above which the gas will heat upon expansion. This is already the case at room temperature and pressure for helium.
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