Carbon Dioxide
Definition and meaning of Carbon Dioxide in chemistry.
Carbon dioxide is a colorless, odorless gas composed of one carbon atom double-bonded to two oxygen atoms, formed whenever carbon-containing fuels or organic matter are fully oxidized. It is a linear, nonpolar molecule that occurs naturally in Earth's atmosphere and is produced by respiration, combustion, and fermentation.
In more detail
The molecule's linear O=C=O geometry gives it no net dipole moment despite polar C=O bonds, so it is nonpolar overall. Carbon dioxide dissolves in water to form a weak, unstable equilibrium mixture containing carbonic acid (H2CO3), which explains the mild acidity of carbonated beverages and rainwater, and its role in ocean acidification. As a greenhouse gas, it absorbs and re-emits infrared radiation, making it central to Earth's climate system and the carbon cycle, and it is the essential carbon source for photosynthesis in plants.
Key facts
| Formula | CO2 |
|---|---|
| Molar Mass | 44.01 g/mol |
| Field | Inorganic Chemistry |
| Geometry | Linear, nonpolar |
When calcium carbonate (limestone) is heated strongly, it decomposes to release carbon dioxide gas: CaCO3(s) → CaO(s) + CO2(g).
Frequently asked questions
Is carbon dioxide the same as carbon monoxide?
No. Carbon dioxide (CO2) has two oxygen atoms and results from complete combustion, while carbon monoxide (CO) has one oxygen atom, forms from incomplete combustion, and is far more toxic.
Why does dry ice not melt into a liquid?
At normal atmospheric pressure, solid CO2 (dry ice) sublimes directly into gas because CO2's triple point (5.1 atm, -56.6 degrees C) lies above 1 atm, so liquid CO2 cannot exist at ordinary pressures.