CENTIGRADE-FAHRENHEITTEMPERATURE CONVERSION In introducing conversion of temperatures to the student, the manner, both in textbook arrangement and pedagogic presentation, appears to be universally a standard one. Yet, the attendant results are a vague, hazy perception and confusion for the student, whether relying upon an independent derivation, as occasion demands, or upon memory of formulas more or less kaleidoscopic in nature, as are the formulas encountered in this work. Most individuals find a need of momentary re-orientation when required to make these conversions, of "starting from the beginning" in order to set the formula aright in mind, while a few may even find it necessary to consult, from time to time, a source of information for the needed formula. These difficulties may be attributed essentially to the 32' transposition involved, which seems to be the barrier. This article not only aims to eliminate restricting ourselves to specific formulas, but especially to indicate a much simpler method of temperature conversion. Rather than commencing at the freezing point of water on the two scales, as has been the custom, let us consider the boiling points. As shown by the figure, between the boilimg and freezing point of water, there are 180 degrees Fahrenheit and likewise 100 degrees centigrade. Then, 100°C. = 180°F.
and,
1°F. =
5'~. 9
We are now in a position to carry out temperature conversions freely, best shown by two examples considered below. (1) 20°C. = ? O F . 20°C. is 80" below the boiling ~oint. Therefore, it is 80 X 9, F.,
5
or 144'F. below the boiling point, which is 68'F. 20°C. = 68OF. (2) 23'F. = ?'C. 23°F. is 189' below the boiling point.
.:
5
Therefore, it is 189 X g°C., or 105'C. below the boiling point, which is -5°C.
VOL.7, NO. 12
TEMPERATURE CONVERSION
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For the individual more mathematically minded, a more direct form of proportion can be introduced, nriz.: 212 - x - -100 - y 212 - 32 100 - 0 or, 212 x - = -100 - y 180 100 where x and y represent the Fahrenheit and Centigrade temperatures, respectively. The points in favor of this method are the comparative simplicity, directness, clarity, and lack of dependence upon memory of formulas or encountered delay in re-orientation to the formulas. The graphical, geometric approach to the idea of proportion tends to make its use in other problem work in elementary chemistry more effective. At the same time a new source of problem material is gained with the introduction of temperature conversion in the study of proportion in courses in plane geometry.
