What part does carbon dioxide play in oxidation



Carbon dioxide is the gas which bubbles from soda water. It is ordinarily found in air in small quantities (about 1 part in every 3000 parts of air). It is slightly heavier, volume for volume, than the rest of the air. Hence it tends to settle close to the earth’s surface. It is sometimes found in considerable quantities in wells and close to the floors of caves.

Carbon dioxide is constantly being added to the air by the oxidation, or burning, of fuel, by the breathing of living things, and by the decay of all sorts of substances. It is estimated that during each hour about two and one half tons of carbon dioxide are breathed into the air by each million human beings. When we consider the innumerable, other living things which breathe out carbon dioxide, it is evident that this gas is constantly being added to the air in enormous quantities.

Carbon dioxide is a colorless gas, like oxygen. Also, like oxygen, it will not burn. But things will not burn in carbon dioxide, as they will in oxygen. Carbon dioxide causes clear limewater to become white.

Carbon dioxide results from the oxidation of materials within the bodies of all plants and animals. It is not a poison, as has sometimes been stated. But if enough of it is present, animals may drown in it in much the same way that they drown in water. The carbon dioxide around them prevents them from getting oxygen, which they must have. There is probably never enough carbon dioxide present, however, even in cities or in crowded rooms, to cause injury.

All green plants use carbon dioxide in their processes of making food, and all return oxygen to the air. Thus they are important in maintaining the oxygen supply.