Laser Measurement of the Speed of Sound in Gases: A Novel Approach to Determining Heat Capacity Ratios and Gas Composition.

• Autores: J. Clayton Baum, R.N. Compton, Charles S. Feigerle
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 85, Nº 11, 2008, págs. 1565-1567
• Idioma: inglés
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• Resumen

  • The speed of sound is measured in several gases using a pulsed laser to create a micro-spark on a carbon rod and a microphone connected to a digital oscilloscope to measure the time-of-flight of the resulting shockwave over a known distance. These data are used to calculate the heat capacity ratios (Cp /CV ) of the gases and the composition of a binary mixture of gases. The application of lasers to the measurement of gas properties provides students with a simple, accurate, and direct, state-of-the-art method for obtaining thermodynamic data. As demonstrated for CCl4 in nitrogen gas, the method is capable of determining the vapor pressure of a liquid�vapor equilibrium in another gas.