carbon dioxide

Carbon Dioxide

Medical grade Carbon dioxide for used in Endoscopies. It is normally recovered for industrial purposes from flue gases or as a by-product of ammonia or hydrogen production. It is unusual in that it only exists as a liquid under pressure and normally sublimes as a gas straight from its solid form.

Like a number of other gases, carbon dioxide's inert qualities make it useful for preventing or suppressing combustion or oxidization. Its major use, however, is as a refrigerant or cooling agent. Solid carbon dioxide at -80°C is, like liquid nitrogen, used for chilling and freezing in the food industry.

The gas dissolves easily in water, making the resultant solution slightly acidic. As a result, it is often used to balance the pH of water in preference to the addition of mineral acids. Its solubility also makes it a chosen method for putting the "fizz" into drinks of all kinds.

Carbon dioxide is a guardian of the pH of the blood, which is essential for survival.

The buffer system in which carbon dioxide plays an important role is called the carbonate buffer. It is made up of bicarbonate ions and dissolved carbon dioxide, with carbonic acid. The carbonic acid can neutralize hydroxide ions, which would increase the pH of the blood when added. The bicarbonate ion can neutralize hydrogen ions, which would cause a decrease in the pH of the blood when added. Both increasing and decreasing pH is life threatening.

Apart from being an essential buffer in the human system, carbon dioxide is also known to cause health effects when the concentrations exceed a certain limit.

Key Properties

Carbon dioxide is a molecule with the molecular formula CO2. The linear molecule consists of a carbon atom that is doubly bonded to two oxygen atoms, O=C=O.

Although carbon dioxide mainly consists in the gaseous form, it also has a solid and a liquid form. It can only be solid when temperatures are below -78 oC. Liquid carbon dioxide mainly exists when carbon dioxide is dissolved in water. Carbon dioxide is only water-soluble, when pressure is maintained. After pressure drops the CO2 gas will try to escape to air. This event is characterized by the CO2 bubbles forming into water.


Carbon dioxide is an essential constituent of tissue fluids. Carbon dioxide needed to supplement various anesthetic and oxygenation mixtures under special circumstances such as cardiac by-pass and the management of renal dialysis.

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