Ideal and real gases ~ MECHTECH GURU

Ideal and real gases

Ideal and real gases

Pure Substance

A pure substance is one  that has a  homogeneous and invariable chemical composition.  It  may exist in more than one phase but chemical composition is the same in all phases.

Some times the mixture of gases, such as air is considered a pure substance as long as there is no change of phase. Further our emphasis will be on simple compressible substances

Early experiments on the variables of state (such as T, P, V, and n) showed that only two of these variables of state need to be known to know the state of a sample of matter.

 1.  Extensive variables

depend on the amount of substance present.  Examples include  the volume, energy, enthalpy, and heat capacity.

2.  Intensive variables:

do not depend on the amount of substance present. Examples include the temperature and pressure.

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