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A concise roadmap for using computational chemistry programs (i.e., Gaussian 03W) to predict the color of a molecular species is presented. A color-predicting spreadsheet is available with the online material that uses transition wavelengths and peak-shape parameters to predict the visible absorbance spectrum, transmittance spectrum, chromaticity diagram, and the standard 24-bit color values, sRGB, at several theoretical concentrations. The technique is demonstrated on azulene derivatives and phenolphthalein. The use of this color-prediction spreadsheet in our introductory chemistry lectures and the physical chemistry laboratory is described along with the applicable topic areas. The theory behind color prediction is explained, but the tool is well-suited for novice users. It has been successful in increasing student engagement with the concepts of spectroscopic absorbance and transmittance while introducing the unfamiliar concepts of standard color spaces.

This article outlines the construction of a large-capacity, digital ring tensiometer, using common laboratory equipment, and reports the validation of this instrument against National Institutes of Science and Technology (NIST) data. A Carver press is used as a hydraulically controlled platform that raises and lowers the temperature-controlled jacketed flask that contains the test solutions. The upper platen of the press supports a four-decimal-place scale with a Pt−Ir ring hanging from the underscale hook. The scale measures the pull on the ring as the solution interface is lowered by the press. The force measurements are transferred to a personal computer (PC) via RS-232 communications. Temperature is controlled via a water-recirculation bath. The experimental surface tension measurements for toluene and water at 13 different temperatures were, on average, 2.7% larger than the NIST data. The 25 °C surface tension measurements for water, 2-butanone, ethyl ethanoate, and toluene were, on average, 1.1% larger than those calculated using the Hansen solubility parameters.

The spectral signatures of nitro attack of the aromatic portion of thermoplastic urethanes (TPU) were determined. Eight fragment molecules were synthesized that represent the nitrated and pristine methylenediphenyl section common to many TPUs. Infrared (IR) and Raman (785 nm illumination) spectra were collected and modeled using the B3LYP/6-31G(d)//B3LYP/6-31G(d) model chemistry. Normal mode animations were used to fully assign the vibrational spectra of each fragment. The vibrational assignment was used to develop a diagnostic method for aromatic nitro attack in thermoplastic urethanes. The symmetric NO(2) stretch coupled out of phase with the C-NO(2) stretch (1330 cm(-1)) was found to be free from spectral interferences. Spectral reference regions that enable correction for physical differences between samples were determined. The carbonyl stretch at 1700 cm(-1) was the best IR reference region, yielding a limit of quantitation (LOQ) of 0.66 +/- 0.02 g N/100 g Estane. Secondary IR reference regions were the N-H stretch at 3330 cm(-1) or the urethane nitrogen deformation at 1065 cm(-1). The reference region in the Raman was a ring stretching mode at 1590 cm(-1), giving an LOQ of 0.69 +/- 0.02 g N/100 g Estane. Raman spectroscopy displayed a larger calibration sensitivity (slope = 0.110 +/- 0.004) than IR spectroscopy (slope = 0.043 +/- 0.001) for nitration determination due to the large nitro Raman cross-section. The full spectral assignment of all eight molecules in the infrared and Raman is presented as supplemental material.