1. The problem statement, all variables and given/known data For a certain experiment, R-410a vapor is contained in a sealed glass tube at 20°C. It is desired to know the pressure at this condition, but there is no means of measuring it, since the tube is sealed. However, if the tube is cooled to −20°C small droplets of liquid are observed on the glass walls. What is the initial pressure? 2. Relevant equations Thermodynamic tables ideal gas equation? 3. The attempt at a solution I set up both states: State 2: T = -20 (saturated) State 1: T = 20, v1=v2=0.0648 P = ? (superheated) I just don't understand how we can figure it out from just the temps. I just cant wrap my mind around the thermodynamic tables.