It is a chemical compound, occurring as a colorless, odorless, tasteless gas that is about +1 times as dense as air under ordinary conditions. It does not burn and will not support combustion of ordinary materials. Its weakly acidic aqueous solution is called Carbonic Acid.

The gas, easily liquefied by compression and cooling, provides the sparkle in carbonated beverages. Solid carbon dioxide, or dry ice, is a refrigerant. Dough rises because of carbon dioxide formed by the action of yeast and baking powder.

Carbon dioxide is a raw material for photosynthesis in green plants, and is a product of animal respiration and of the decay of organic matter. Carbon dioxide occurs both free and combined in nature and makes up about 1% of the volume of the dry air. It can cause death by suffocation if inhaled in large amounts.