Difference Between Carbon Dioxide and Carbon Monoxide

Carbon Dioxide vs Carbon Monoxide | CO vs CO2

Both the compounds, Carbon Dioxide and Carbon Monoxide, are made with carbon and oxygen. They are gases and are formed in the combustion of carbon containing compounds.

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 emit to the atmosphere through natural processes like respiration, volcano eruption, and 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, and global warming have resulted as a consequence of that. Carbon dioxide is used to make soft drinks, in the bakery industry, as fire extinguishers, etc.

In biological systems, carbon dioxide is produced as a by-product of cellular respiration. This carbon dioxide should be removed from cells, and then it is excreted to the external environment via lungs. There are three ways of transporting carbon dioxide from cells to lungs. One way is to bind with hemoglobin and form carbaminohemoglobin. Further, carbon dioxide can be dissolved in blood plasma and can be transported. The most common way to transport carbon dioxide is to convert it to bicarbonate ions by carbonic anhydrase enzyme in the red blood cells.

Carbon Monoxide

Carbon monoxide is also a molecule formed by carbon and oxygen. One carbon atom is bound to an oxygen atom with three bonds, and the molecule has a linear geometry. Among two bonds, two are covalent bonds and one is a dative bond. It is a colorless, odorless and tasteless gas, and it is slightly lighter than air. The molecular weight of CO is 28 g mole-1. CO is considered as a polar molecule due to the electronegativity difference between the carbon and oxygen. CO is produced from the partial combustion of organic compounds. Carbon monoxide is also produced in biological systems in minute quantities. However, when people inhale large amount of CO from the external environment, it can cause death. CO has a higher affinity to hemoglobin than oxygen and forms carboxyhemoglobin complexes, which are quite stable. This lowers the amount of available hemoglobin for oxygen transportation to cells, thus cause cell death.

What is the difference between Carbon Dioxide and Carbon Monoxide?

• In carbon dioxide, two oxygen atoms are bound to one carbon, but, in carbon monoxide, only one oxygen atom is bound to carbon.

• In CO2, there are only covalent bonds. But in CO, there is a dative bond other than two covalent bonds.

• CO can have resonance structures, but CO2 cannot.

• Carbon dioxide is denser than air, but carbon monoxide is slightly lighter than air.

• CO is a polar molecule, whereas CO2 is a non polar molecule.

• Carbon dioxide forms carbaminohemoglobin complex with hemoglobin, but CO forms carboxy hemoglobin complex.

• Higher concentrations of CO are highly toxic to humans than CO2.

• CO is formed when there is not enough oxygen gas to oxidize carbon containing compounds. Basically, CO is formed in partial combustion of carbon containing compounds, and in full combustion, CO2 is produced.