Chemical Education Today
Letters A Simplified Algorithm for Temperature Conversions As pointed out by Mitschele (1), the application of the classical formulas for conversions between Celsius (C) and Fahrenheit (F) temperature scales has been a source of confusion for students and professionals alike. I am surprised that those who teach temperature conversion formulas have not introduced the easier-to-retain relationship based on the fact that ⫺40 F⬚ is the same temperature as ⫺40 C⬚. This method derives from the symmetrical relationship between the Celsius and Fahrenheit temperature scales: (F ⫹ 40) ⫽ 9/5 (C ⫹ 40). This relationship is easily obtained from the classic relationship, F ⫽ (9/5) C ⫹ 32, by adding 40 to each side of the equation, and then factoring 9/5 on the right side. The con-
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version is a three-step procedure, regardless of the direction of conversion: 1. Add 40 to the seed number, either F or C 2. Multiply by the appropriate slope, either 9/5 or 5/9 3. Subtract 40 from the product to obtain the final result
Literature Cited 1. Mitschele, Jonathan. J. Chem. Educ. 2002, 79, 1235–1236. Victor G. Mossotti U.S. Geological Survey Menlo Park, CA 94025
[email protected] Journal of Chemical Education • Vol. 80 No. 12 December 2003 • JChemEd.chem.wisc.edu
