Carbonation[1]​ is the chemical reaction of carbon dioxide to give carbonates, bicarbonates and carbonic acid.[2]​ In chemistry, the term is sometimes used instead of carboxylation, which refers to the formation of carboxylic acids.

In inorganic chemistry and geology, carbonation is common. Metal hydroxides (MOH) and metal oxides (MO) react with CO to give bicarbonates and carbonates:

In reinforced concrete, the chemical reaction between carbon dioxide in the air and hydrated calcium hydroxide and calcium silicate in the concrete is known as neutralization. The similar reaction in which calcium hydroxide in cement reacts with carbon dioxide and forms insoluble calcium carbonate is carbonation.

Henry's law states that Henry's law states that at a constant temperature, the amount of gas dissolved in a liquid is directly proportional to the partial pressure that that gas exerts on the liquid.[3]​ This law is actually a chemical balance of solubility of gases in liquids and as such, it can be expressed by the equation:

where P is the partial pressure of the CO gas above the solution. K is Henry's law constant and x is the mole fraction of CO gas in the solution. K increases with temperature, causing the mole fraction of carbon dioxide that dissolves in water to become smaller. Consequently, carbonation increases in a solution as the temperature decreases.[4]​ On the other hand, if the partial pressure of CO increases, the mole fraction of CO in solution has to increase, favoring carbonation.