NO2/N2O4 Equilibrium Experiment
Teresa Anderson Curtin University of North Carolina at Chapel Hill, Chapel Hill, NC 27514 Darryl Wahlstrom Huron High School, Ann Arbor, MI 48109 James A. McCormick University of Wisconsin- Madison, Madison, WI 53706
Note:	This program is out of print.
NO2/N2O4 Equilibrium Experiment introduces the student to the use of computers to collect experimental data, analyze the data collected, and incorporate the results of the analysis into a laboratory report. As its name suggests, it focuses on a study of the chemical equilibrium that exists between gaseous dinitrogen tetroxide (N2O4) and gaseous nitrogen dioxide (NO2). Students measure the absorbance of a mixture of NO2 and N2O4 as a function of temperature between 25 and 100 degrees Celsius. The data are obtained by interfacing the game-control port of an IBM microcomputer to a colorimeter called a Blocktronic. Directions for building the Blocktronic are included in the documentation. The computer's game-control reading of the gas sample is converted to an absorbance reading by utilizing calibration data from the Blocktronic. Once the absorbance of NO2 at the various temperatures is recorded, the values for the equilibrium constant, Kp, can be determined at each of the temperatures. Lastly, the equilibrium constant results are analyzed graphically to arrive at values for the changes in enthalpy, delta-H, and entropy, delta-S. Hardware and Software Requirements NO2/N2O4 Equilibrium Experiment requires a MS-DOS/IBM compatible computer with at least 512K RAM and one disk drive. It supports (but does not require) an Epson or IBM compatible graphics printer. NO2/N2O4 Equilibrium Experiment requires CGA or compatible graphics and supports (but does not require) a Microsoft compatible mouse; a Blocktronic (1, 2) or Blocktronic II (3) colorimeter must be attached to the computer through a modified cable (directions included) and a game-port card (not included). Literature Cited Adams, T., et al. "Instructions for Building the Blocktronic I" (version 2.1); LM002; Project SERAPHIM: University of Wisconsin-Madison, Department of Chemistry, 1101 University Avenue, Madison, WI 53706. Miles, P.; Brickhouse, N. and Moore, J. W. "Adapter Box for the IBM PC"; LM022; Project SERAPHIM: University of Wisconsin-Madison, Department of Chemistry, 1101 University Avenue, Madison, WI 53706. Divis, L.; Krause, D. "Blocktronic II Colorimeter"; J. Chem. Educ: Software 1988 IA (1), 3952.

First Published: October 1991

Citation: Curtin, T. A.; Wahlstrom, D.; McCormick, J. A. . NO₂/N₂O₄ Equilibrium Experiment J. Chem. Educ. Software 4B2

Keywords: Laboratory; General; Physical; Equilibrium calculations; Lab Interface - PSL

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