Subject: How to calculate the internal pressure of a closed container as its heated?

I am trying to understands what involves in the calculation of internal 
pressure for a closed container which is half filled with water and the other 
half is filled with inert gas. From understanding, without inert gas, the 
internal pressure will be generated from the vapor pressure of water and 
possibly the henry law- P = kC (of air?). However, since there exist inert 
gas, is P= nRT/V the correct equation to use for the pressure from the inert 
gas? In both cases, what would the volume be? As the temperature increased, 
the water volume could possibly increased thus shrinking the space for the 
inert gas. However, gas expands as the temperature increased. Meaning that the 
volume for inert gas also increased as temperature increased. I am quite 
confused with this and hope to get advice on this matter. Thanks a lot!

Re: How to calculate the internal pressure of a closed container as its heated?