> > A recent discussion with a colleague left me looking for a formula to
> > calculate the temperature of a given gas as a function of volume.
> >
> > I understand PV=nRT, but what if I only change the volume and want to
> > calculate both the new temp and pressure? I expect there's an equation
> that
> > relates specific heat, temperature and volume, but I haven't been able
> to
> > find it with google (probably a bad choice of search terms), a little
> help?
>
> Presenting the one and only combined gas law:
> (P1 x V1) / (P2 x V2) = T1/T2
>

But that's just a simplified case of PV=nRT. PV=nRT can be rewitten to
  P1 V1         P2 V2
----------  = ----------
 n1 R T1       n2 R T2

When n (number of moles of gas) is constant, n1=n2 and that term cancels.
And since R is a constant, it cancels- leaving your equation.

What I'm looking for is an expression that relates temperature to quantity
of gas, volume, specific heat (a property of a specific gas) and some
quantity of heat (calories, joules, BTUs, whatever)

I need to be able to answer questions like: what is the temperature and
presure of a mole of gas X in a container of size Y if it contains Z
calories of heat. And: If a sample of gas X at temperature and pressure Y
and Z is compressed to volume W, what is the final temperature and presure.
PV/T is not enough to solve these.

-Denny


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