Carbon dioxide and carbon dioxide, CO2 formula is also called. It is a heavier than air gas: density 1.52, colorless, smell and taste somewhat spicy, incombustible, incomburente and suffocating. Express it some volcanoes and some cracks in the ground. In addition it originates by respiration of animals and plants, burning, rotting and fermentation of organic substances.Used in sparkling beverages, fire extinguishers and medicine. Solidified constitutes the "dry ice", used in refrigeration. Improperly called carbonic acid. It is the combination of the dioxide with water: H2O = CO3H2 CO2. This property is more correct nomenclature of anhydride, because combined with water oxides do not generate acids, but chemical bases: hydroxides.