# Compressible Factor

I 've a soft question on the terminology of compressibility factor. It is termed compressible factor because, its value determines how any reals gas is compressible with respect to an ideal gas according as its value-less than or greater than 1. If $Z>1$ then $\frac{pV}{nRT}>1$ and so $p>\frac{nRT}{V}$ which means it is more compressible than ideal gas. Because for ideal gas it is $p = \frac{nRT}{V}$. Simillar for negative deviation. But the question arises why we have not taken $V$ on LHS in these equations and inequations. I mean why does scientists doesn't named this as something like "volumetric factor" (actually can't find any specific word, but it is not important, hope readers can understand my question.) I mean something like Volume is greater than of ideal gases.

And another one is we always have graphs of $Z \rightarrow p$ to understand the deviation in real gases from ideal gases. (I'm posting a graph for instance.) Why we don't take $T$ or $V$ on the X-axis to understand this concept.

I look at it in a different way; not about volume but rather the relationship between molar volume and 'ideal' molar volume, $\frac{V}{n}$ and $\frac{RT}{P}$.
From $PV = ZnRT$ write
$$\frac{V}{n} = Z\frac{RT}{P}$$