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The First Law
The first law of thermodynamics
states the principle of energy conservation for systems in which
heat and work interactions can take place and the internal energy of the system
can change. Using unit mass or molar quantities the First Law has the form:
du = d'q - d'w
The heat interaction, d'q,
is positive if heat is added to the system. The symbol, d' ,is used to indicate
that the process is path dependent (d'q is an inexact differential).
The
work interaction, d'w, is positive if work is done by the system.
The work interaction is path dependent and d'w is an inexact differential.
The
change in the internal energy, du, depends only upon the initial and
final state of the system and NOT on the path taken between the end points.
du is an exact differential.
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