Question

The vapor pressure of nitrogen at several different temperatures is shown below.
Temperature Pressure ()
65 130.5
70 289.5
75 570.8
80 1028
85 1718

Use the data to determine the heat of vaporization of nitrogen.

Determine the normal boiling point of nitrogen.

Answer 1

Use the Clausius-Clapeyron equation. A P1 and P2 together with T1 and T2 will get delta Hvap. I might do two or three to see how they agree and take an average. After delta Hvap is determined, you can go to one of the P values (I would choose the pressure closest to the boiling point of N2--you can look that up on the web) and the T for one set of data, then use 760 mm P for the other pressure point and T that corresponds to that will be the boiling point. (The idea here is that the boiling point of a liquid is defined as the temperature at which the vapor pressure of the liquid equals atmospheric pressure. (Remember that's why water boils below 100 C at the top of Pike's Peak. Don't forget to use T in Kelvin.

Answer 2

5.912