Analysis of carbon dioxide CO2 Carbon dioxide (CO2) is a colorless gas, first discovered in 1577 by Van Helmont who detected it in the products of both fermentation and of coal combustion. CO2 is used in solid, liquid and gaseous forms in a variety of industrial processes. These include: beverage carbonation, dry ice, welding and chemical manufacturing. It is produced by the combustion of all carbonaceous fuels and can be recovered in numerous ways. Today it is widely used as a by-product of synthetic ammonia production, fermentation and combustion gases by absorption process. CO2 is also a product of animal metabolism and is important in the life cycles of plants and animals. It is present in the atmosphere only in small quantities (0.03% vol.). CO2 is not very reactive at normal temperatures, but forms carbonic acid (H2CO3) in aqueous solution. This will undergo the typical reactions of a weak acid to form salts. I call it carbonic acid because in the presence of moisture, which we have around us, it will produce an acid. CO2 is also responsible for the acidic pH of rainwater. So that nasty thing called “acid rain” is caused by CO2. A hydrated solid CO28H20 separates from aqueous CO2 solutions which are colder at high pressures. It is very stable at normal temperatures, but forms CO and O2 when heated to temperatures above 1700°C. CO2 can be reduced by several methods, the most common of which is reaction with hydrogen (H). This is the inverse of the water gas shift reaction, commonly used in the production of hydrogen and ammonia. It can also be reduced with hydrocarbons and carbons at elevated temperatures. The CO2 will react with ammonia to form ammonium carbonate. CO2 + NH3 ---à NH4 + CO3. We humans also produce CO2 with every breath we take, but the amount is too small to harm anyone. However, carbon dioxide can be dangerous at higher levels. Only 5% vol.