What is the chemical formula for carbon dioxide? Carbon dioxide has the chemical formula CO₂: one carbon atom bonded to two oxygen atoms.
The molecule is linear, with carbon in the center and an oxygen atom on each side. The two C=O double bonds make the formula CO₂, while CO describes carbon monoxide, a different compound. CO₃ is not the ordinary molecular formula for carbon dioxide; carbonate compounds contain the carbonate ion, CO₃²⁻.
Carbon dioxide is naturally released by respiration, decomposition, volcanic activity, and combustion. Plants, algae, and cyanobacteria use it in photosynthesis, converting carbon dioxide and water into energy-rich carbohydrates and releasing oxygen.
In the eighteenth century, Joseph Black studied the gas he called “fixed air.” Solid carbon dioxide is commonly known as dry ice and changes directly into gas at ordinary atmospheric pressure, rather than forming a liquid.