The molecular wieght of diatomic nitrogen and diatomic oxygen are 28 and 32, respectively. Both of these compounds are gases under atmospheric conditions. The molecular weight of water, on the other hand, is 18, and it is a liquid because of its ability to form these h-bonds. The apparatus itself is closed once the initial preparation is complete. While purging, the apparatus is brought to thermal equilibrium.
Temperature is maintained by a P controller hooked up to a home-made heating coil.
A typical data set will consist of approximately 20-30 spectra at one temperature. Once recorded, the spectra are processed to isolate the specific peaks in the IR spectrum relevant to this study. This process will eventually yield data describing the degree of hydrogen bonding taking place in the system. The degree of h-bonds, as mentioned earlier, varies with temperature, so multiple runs are made at different temperatures. If this page has just whetted your appetite for the thermodynamics of hydrogen bonding, try checking out the article I co-wrote with my research advisor, Dr. Ram Gupta , in the January 1998 issue of the AIChE Journal.