Calculate Methane Volume from Pressure, Temp & Density?

[glocki35]

Homework Statement

Can I calculate the volume of Methane if I have the pressure, Temperature and the density?, this is required to calculate the number of moles (n) for Methane, which is given by n = total gas weight / molecular weight, I can not get the total gas weight unless I calculate the volume, I am totally stuck, can anyone help?

Homework Equations

The Attempt at a Solution

 

[sjb-2812]

What kinds of pressures are you talking about? Under most conditions, the ideal gas equation is a pretty good approximation to the truth, what does that state?

 

[glocki35]

HI sjb-2812, this is not for an ideal gas so I have to use the Z compressibility factor, I have already calculated Z i.e PV=ZnRT, these are the knowns;
z=0.81, R=10.73 psia...T=580 Deg P=2195 psia n = ??at reservoir conditions, for standard conditions these are the knowns- Zsc=1.0, R=10.73, Tsc = 520 Deg R, Psc=14.7 psia & n = ??, this is all of the information I have, I am attempting to find the number of moles n (n=volume at reservoir conditions / volume at standard conditions) by finding the gas density and in turn the volume so I can calculate Bg the gas FVF (formation volume factor), I know how to find the gas density, however how do you find the gas volume with this information?, this is where I am stuck, perhaps my reasoning in flawed, I just don't know...thanks