1. The problem statement, all variables and given/known data The following link shows the variation of vapor pressure with temperature. In which way the data should be plotted to obtain a straight line? http://www.chem.purdue.edu/gchelp/liquids/vpress.html 3. The attempt at a solution For this, I need to know exactly the mathematical relationship which I can't seem to find anywhere. Anyways, my immediate guess would be that the graph is an exponential function. So plotting the graph of lnP vs T would give me a straight line but the correct answer is lnP vs 1/T. I'm sure I'm missing something here.