Difference Between Oxygen and Carbon Dioxide

Oxygen vs Carbon Dioxide

Oxygen and carbon dioxide gases are two crucial constituents in the earths’ atmosphere. This is due to its importance for living organisms. Oxygen is needed for respiration, and carbon dioxide is emitted in the process. This inhaled oxygen is needed to produce energy (ATP) inside living cells from the process known as cellular respiration. On the other hand, carbon dioxide is utilized by plants for photosynthesis to produce carbohydrates. So, plants are involved in maintaining the oxygen, carbon dioxide balance in the atmosphere.


Oxygen is the element with the atomic number 8, which is present in group 16 of the periodic table. Oxygen has three isotopes, 16O, 17O, 18O. Among these 16O is the most abundant isotope. Oxygen atom has eight electrons, and it can obtain two more electrons from another atom to form a -2 charged anion. Alternatively, two oxygen atoms can share four electrons to form a diatomic molecule (O2) to be stable. Molecular weight of O2 is 32 g mole-1. Three atomic form of oxygen, which is also known as ozone is another common form of oxygen. Molecular oxygen is a colorless, odorless gas. There is about 21% of oxygen in the earths’ atmosphere. It is poorly soluble in water and is slightly heavier than air. Oxygen reacts with all the elements to form oxides except inert gases. Therefore, it is a good oxidizing agent. Oxygen is essential in respiration of living organisms and also for the combustion. Oxygen is used in hospitals, welding, and in many other industries.

Carbon Dioxide

Carbon dioxide is a molecule form from a carbon atom and two oxygen atoms. Each oxygen atom forms a double bond with carbon, and the molecular has a linear geometry. The molecular weight of carbon dioxide is 44 g mole-1. Carbon dioxide (CO2) is a colorless gas and upon the dissolution in water, it forms carbonic acid. Carbon dioxide is denser than air. Concentration of carbon dioxide is 0.03% in the atmosphere. Through carbon cycle, the carbon dioxide amount in the atmosphere is balanced. Carbon dioxide can be emitted to the atmosphere through natural processes like respiration, volcano eruption, and also through human activities like fossil fuel burning in vehicles and factories. Carbon dioxide is removed from the atmosphere in photosynthesis, and they can be deposited as carbonates in the long run. The human interference (fossil fuel burning, deforestation) has caused an imbalance in the carbon cycle, increasing CO2 gas level. Global environmental problems like acid rain, green house effect, global warming has resulted as a consequence of that. Carbon dioxide is used to make soft drinks, in bakery industry, as a fire extinguishers, etc.

Oxygen Vs Carbon Dioxide

- Oxygen is a diatomic molecule, and carbon dioxide has three atoms.

- Oxygen concentration is higher in the atmosphere than carbon dioxide concentration.

- Carbon dioxide is an acidic gas. When it dissolves in water it forms carbonic acid. Oxygen is poorly soluble in water, and it doesn’t have an acidic nature.

- Oxygen is used for respiration in living organisms, and as a by-product in that process carbon dioxide is synthesized.

- In O2, oxygen is in the zero oxidation state, but in CO2, oxygen is in -the -2 oxidation state.