Equation of state

Equation of state


An equation of state is an equation which relates the
variables of state (T, P, V, and n). It’s particularly useful when you want to
know the effect of a change in one of the variables of   state


 1. Solids and Liquids


    If the pressure on a solid or
liquid is increased, the  volume does not
change much. If  the temperature is
increased, the volume doesn’t change much either. Therefore, an appropriate equation of state describing such systems would be: V(T,P) = constant.


2. Gases


 In contrast, changing the
pressure or temperature of a gas will have an 
easily  observable effect on the
volume of that gas. For an ideal gas (no
intermolecular interactions and no molecular volume) n appropriate equation of
state would be: V(T,P,n) = (nRT)/P.

There are many equations of state describing real gases. These equations take in
consideration molecular volume and interactions. The most
  well-known 
such  equations is probably the
Van der Waals
equation.

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