How does pressure affect the phase transition from gas to liquid?

[oneat]

If I Press gas to a pressure in which it changes to liquid. What would be temperature of this liquid after?

 

[johng23]

Unary phase diagram:

http://wikis.lib.ncsu.edu/images/9/9c/CH434_575px-Phase-diag.svg.png

At any temperature higher than the triple point temperature (but below the critical point), there is some pressure at which the gas and liquid will coexist. The exact curve depends on the substance you are compressing.

So if you fix the temperature, you can compress the gas until it liquifies. If you are not holding the temperature fixed, the behavior has to depend on whatever constraints you are imposing.