DUHEM’S THEOREM
Duhem’s Theorem states that, for any closed system formed initially from
given masses of prescribed chemical components, the equilibrium state is
completely determined when any two independent variables are fixed. In that
sense, for a given system, two independent variables should be distinguished: the
intensive and/or the extensive variables, wherein the phase rule can find out the
former.
One situation where Duhem’s Theorem is applied in the industry is through
distillation. Distillation is the most extensively used commercial method of
separating fluid mixtures, and it is thus a significant aspect of many operations in
the oil and chemical industries. It is used to separate liquids from nonvolatile solids,
such as alcoholic liquors from fermented materials, or two or more liquids with
different boiling temperatures, such as gasoline, kerosene, and lubricating oil from
crude oil. As the Theorem indicates, an equilibrium state can be reached if two
variables are determined; this can be applied in a distillation process since in order
for this system to operate successfully, it considers various factors and variables to
reach the highest efficiency possible.
There are two phases present in the said system, and likewise, there are
usually two components as well. The separation of ethanol from water is one
example of a distillation process, maybe the most well-known, and hard liquors
