For a certain experiment, the R-134a vapor is contained in a sealed glass tube at 20 ° C. You want to know the pressure under these conditions, but there is no means of measuring it since the tube is sealed. However, if the tube is cooled to -20 ° C, small drops of liquid are observed on the glass walls. What is the initial pressure?

For a certain experiment, the R-134a vapor is contained in a sealed glass tube at 20 ° C. You want to know the pressure under these conditions, but there is no means of measuring it since the tube is sealed. However, if the tube is cooled to -20 ° C, small drops of liquid are observed on the glass walls. What is the initial pressure?