[sid95]

In most books Z is described as a function of pressure and temp. Istnt it a function of volume too?

[Jorriss]

So, indirectly, it seems by asking if it depends on volume you're asking is the compressibility factor an intensive or extensive property aka does it depend on how much there is?

And, while this is a question I'm unfamiliar with, my initial thoughts are no, it doesn't depend on the amount present as long as it's enough to obey statistical stuff.

By compressing it you want to overcome intermolecular forces and those won't be affected, in any appreciable way I can think of, by having more of a substance.