We are developing quick, cheap, and easy methods for determining physical properties of solutes (molecular weights, activity coefficients, ionization constants, critical micelle concentrations).  The methods rely on new instruments with which we can make accurate measurements with less waste than with conventional instruments or wet methods.  These instruments measure the number of particles in the solutions that result from dissolving the solute and from its dissociation in water.  The measurements are rapid (< 1 min) and require volumes of only about 250 ?L (2.5 x 10-4 L) or just a few drops of liquid.  One such instrument is the computerized freezing point depression apparatus. It works well for determining molecular weights.  However, it makes measurements on solutions at 0 ?C or slightly lower, rather than at room temperature (25 ?C).  Chemists usually want activity coefficients and ionization data at room temperature.  Another instrument that can measure the concentration of ions in solution is the vapor pressure osmometer.  The advantage of the vapor pressure osmometer is that it works at room temperature.  After we have adapted existing methods for determining these physical properties to the vapor pressure depression and freezing point depression osmometers, we will compare the results from the osmometers to conductivity measurements and traditional colligative property measurements to see if they are interchangeable.  We hope these methods will supplant some of the methods in current use.

  *  C. Ashley Loflin is the undergraduate research student and presenter.
 ** Judith M. Bonicamp is the faculty mentor.