Accession Number : ADA299833

Title :   Equilibrium-Vapor Cell for Quantitative Infrared Absorbance Measurements.

Descriptive Note : Final rept. Jul 93-Feb 94,

Corporate Author : VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG

Personal Author(s) : Field, P. E. ; Combs, R. J. ; Knapp, R. B.

PDF Url : ADA299833

Report Date : AUG 1995

Pagination or Media Count : 30

Abstract : Infrared (IR) absorbance measurements, through a gas flow cell, are made with the closed-loop circulation of vapor-air mixtures that are generated by temperature equilibrated aqueous solutions. Accurate vapor pressures of organic solutes are established with the equilibrated aqueous solutions. The water solvent effectively depresses the vapor pressure associated with the pure organic solutes of methanol, ethanol, isopropanol, acetone, and methyl ethyl ketone (MEK). Knowledge of the solute liquid mole fractions, pure component vapor pressures, and the Wilson equation permit determination of the solute vapor pressures to within 2% accuracy. Reliable solution preparation requires only the correct weighings of pure constituent materials before mixing to achieve the targeted solute liquid mole fractions. Absorbances are measured for all solutes over a range of seven concentrations with the exception of four MEK concentrations. These concentrations show the absorbance region of adherence to Beer's Law with an experimental precision of approximately +2% for the solutes studied. Absorptivities that are calculated from the absorbance versus vapor pressure slopes are compared to the available IR absorbance data from other laboratories.

Descriptors :   *VAPOR PRESSURE, *INFRARED EQUIPMENT, *CHEMICAL EQUILIBRIUM, MEASUREMENT, TEMPERATURE, PREPARATION, SOLUTIONS(MIXTURES), METHYL RADICALS, LIQUIDS, WATER, CELLS, MATERIALS, PURITY, RELIABILITY, METHANOLS, SOLUTES, SLOPE, SOLVENTS, ABSORPTION, ACETONES, CIRCULATION, GAS CELLS, CLOSED LOOP SYSTEMS, ETHYL RADICALS, GAS FLOW, KETONES, FOURIER SPECTROSCOPY, PROPANOLS, ORGANIC SOLUTES.

Subject Categories : Physical Chemistry
      Organic Chemistry
      Atomic and Molecular Physics and Spectroscopy
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE