The Weight of Gases
المؤلف:
GEORGE A. HOADLEY
المصدر:
ESSENTIALS OF PHYSICS
الجزء والصفحة:
p-165
2025-11-11
39
Though gases are the lightest forms of matter, each has weight, as may be found by weighing.
Demonstrations. - Weigh on a delicate balance a light glass flask that is fitted with a stopcock. Exhaust the air from the flask and weigh it again, and the flask and contents will be found to be lighter than before.
Weigh carefully an incandescent lamp bulb. One. with a broken filament will answer, and one with a light base is desirable. Direct the point of a blowpipe flame upon one side of the bulb. As soon as the glass becomes red-hot it is forced in by the pressure of the atmosphere, and if only the point of the flame is used, a small, round hole will be blown in the bulb. The filament will probably be blown in pieces, but the pieces will all be inside the bulb, and there will be no loss of weight on account of losing any of them. Weigh the bulb a second time, and the difference in weight will be the weight of the air that has entered the bulb.
By an extension of these methods the weight of air and other gases has been found., The weight of 1 c.c. of dry air at 0° C. and the barometric pressure of 760 mm. is 0.001293 g. Since 1 c.c. of water at 0° C. weighs practically 1 g., the weight of air is 1/773 of the weight of water.
Hydrogen, the lightest known gas, weighs 0.0000899 g. per cubic centimeter; hence air is about 14.4 times as heavy as hydrogen. The weight of air in English measure is 0.33 grain per cubic inch, of hydrogen 0.0228 grain, and of carbon dioxide 0.5046 grain.
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