Energy, Work, and Heat The First Law of Thermodynamics

The heat and the work supplied to a system are withdrawn from the environment, such that, according to the first law of thermodynamics. 

The terms of type X dY in Equation 3.4 represent mechanical (volume), interfacial, electrical, and chemical works, respectively., implies summation over all components in the system. It is obvious that for homogeneous systems the y dA term is not relevant. 

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