Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
Britannica Sources used in this answer

What is the difference between carbon monoxide and carbon dioxide?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
A labeled diagram of the periodic table entry for carbon, showing its atomic number 6, symbol C, electron configuration, atomic weight range, solid physical state, hexagonal crystal structure, and weakly acidic oxide properties. Color coding and icons indicate it is a nonmetal, solid at room temperature, with hexagonal structure and weak acidity.
carbon Carbon and its properties.

Carbon monoxide (CO) and carbon dioxide (CO₂) are distinct oxides of carbon with significantly different properties and biological effects.

Key Differences

  • Chemical Composition and Formation: Carbon monoxide is produced by the incomplete combustion of carbon-containing fuels, whereas carbon dioxide is the product of complete combustion, respiration, and fermentation.12
  • Biological Impact: Carbon monoxide is a highly toxic, dangerous asphyxiant because it binds to hemoglobin in the blood more readily than oxygen, preventing oxygen transport to tissues. In contrast, carbon dioxide is a natural component of the atmosphere; it acts as an asphyxiant only in very high concentrations, while in small amounts, it actually stimulates breathing.13
  • Environmental Role: Carbon dioxide is a significant greenhouse gas that contributes to global warming by trapping radiant energy in the atmosphere. Carbon monoxide is primarily recognized as a major air pollutant and an indicator of air quality.241
  • Physical Properties: Carbon monoxide is a flammable, colorless, and odorless gas. Carbon dioxide is a colorless gas with a faint, sharp odor and a sour taste; it is non-flammable and can be compressed into dry ice.12