Re: Does a Gas with a Net Charge have larger Molar Volume?

A gas with a net charge would exert additional pressure due to
the repulsive force of the charged gas molecules.  (Note that this
would be a difficult experiment to do, because the gas would tend
to neutralize itself by transferring charge to the container.)
So far as I know, this experiment has not been done, so I don't
know of any empirical formulas to characterize the effects.

The volume charge density would not be uniform throughout the gas,
because the repelling charges would separate as widely as possible,
pushing the charge to the surface of the volume.  Thus the effective 
pressure increase depends on the size and shape of the container.
The temperature of the gas would not have to rise, although it's
hard to see how one could add charge without adding heat.  For 
example, you might try to charge up the gas by sending a beam of
charged particles through it.  In this case, the energy of the
particle beam would add heat to the gas.