Absorption of Gases by Solids
المؤلف:
GEORGE A. HOADLEY
المصدر:
ESSENTIALS OF PHYSICS
الجزء والصفحة:
p-184
2025-11-12
48
Some porous solids have the property of absorbing gases to a great extent, a given body of the solid absorbing many times its own volume of the gas. Demonstration. - Trim a piece of charcoal about an inch long so that it will slip easily into a large test tube. Invert the tube and fill it with ammonia gas. Pour mercury into a dish and place the piece of charcoal on its surface. Bring the test tube down over the charcoal and fix it in such a position that its mouth will be a little below the surface of the mercury. In a short time, the charcoal will absorb the ammonia, and the mercury will rise in the tube, as in Fig. 1.
A most important application of the gas-absorbing property of charcoal has been made in the construction of gas masks to absorb poisonous gases. The degree to which the absorption is carried depends largely upon the character of the charcoal used. This is determined not only by the material from which the charcoal is made, but also by the process of manufacture. Charcoal made from coconut shell and peach stones is of high absorptive quality and is capable of being broken into small pieces, thus increasing its surface, without crumbling into dust.
The charcoal, with soda, lime, and cement granules, is placed in an absorbing chamber or canister and moistened with a suitable chemical solution, sodium hyposulphite, for example, for the absorption of chlorine.
While primarily made for the protection of soldiers in war, the gas mask has many uses in times of peace, such as protection against noxious gases in coal mines. The mask shown in Fig. 2 is for protection against ammonia fumes. The air inhaled passes first through a canister containing the prepared charcoal. The exhaled air is released through a flutter valve in front of the neck.
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