Equilibrium-Vapor Cell for Quantitative Infrared Absorbance Measurements.
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1995
- Accession Number
- ADA299833
Entities
People
- P. E. Field
- R. B. Knapp
- R. J. Combs
Organizations
- Virginia Tech