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Curve of Heat Effects

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-285

2025-11-25

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An effective way of showing the relation between the heat units applied and the effects produced is indicated in Fig. 257. This shows graphically the relation between the heat units and the changes produced when heat is applied to 1 g. of ice at - 18° and continued until the latter is changed into steam at 120°. Horizontal distances represent calories or heat units (H. U.), and vertical distances represent changes of temperature.

Since the specific heat of ice is 0.502, Mts = 1 x 18 × 0.502 = about 9 calories required to raise the ice to zero. 80 calories will be required to melt it; 1 × 100 × 1 = 100

calories to raise the water to 100°; 537 calories to vaporize it; and, since the specific heat of steam is 0.48, Mts = 1 X 20 × 0.48 = 9.6 calories to raise the steam to 120°. The total heat applied will be the sum of these amounts, or 735.6 calories.

A study of this curve will be of great assistance in making clear the relation between heat units, specific heat, heat of fusion, and heat of vaporization, and will help in the solution of problems that include these quantities.