Carbon Monoxide

Carbon monoxide (CO) is an inorganic compound with the formula CO. It is industrially produced on a large scale and is used to manufacture numerous organic and inorganic compounds. However, as a flammable and toxic gas, it must be handled cautiously.

1.0Introduction 

Carbon monoxide (CO) is an inorganic dative covalent molecule. It is produced on a large scale in the industrial sector due to its utility in synthesizing various organic and inorganic compounds. However, as a volatile and dangerous gas, CO must be handled with extreme caution.

The first recorded observation of carbon monoxide was by the Greek philosopher Aristotle, who noted that burning coal produces this gas. In 1776, French chemist de Lassone produced carbon monoxide by heating zinc oxide (ZnO) with coke. However, he mistakenly believed the gas was hydrogen because it burned with a blue flame. It wasn't until 1800 that Scottish chemist William Cruickshank correctly identified the gas as a combination of carbon and oxygen.

2.0Structure of Carbon Monoxide

A carbon monoxide molecule has one carbon atom and one oxygen atom connected by two pi bonds and a sigma bond, forming a triple bond. Both atoms follow the octet rule, creating a stable triple bond. Carbon monoxide exhibits sp hybridization, resulting in a linear structure with a bond angle of 180° and a bond length of 112.8 pm.

3.0Sources of Carbon Monoxide

Carbon monoxide (CO) is emitted during combustion, particularly when combustion is incomplete.

The major outdoor carbon monoxide (CO) sources include road traffic with vehicles and combustion engines, power plants, wildfires, and residential heating, mainly from wood burning.

Numerous indoor sources of CO include paraffin, propane, and gas heaters, fireplaces, boilers, and other fuel-burning appliances. Improper use or faults in these appliances can significantly affect indoor air quality. Additionally, tobacco smoke is a notable indoor source of CO.

4.0Physical Properties of Carbon Monoxide

• Molecular Mass: Carbon monoxide has a molecular mass of 28.010 g/mol.
• Density: The density of carbon monoxide is 789 kg/m³.
• Appearance: It is a colourless and odourless gas.
• Melting Points and Boiling Points: Carbon monoxide's melting point is -205.02°C (68.13 K), and its boiling point is -191.5°C (81.6 K).
• Solubility: Carbon monoxide is sparingly soluble in water but more soluble in solvents such as chloroform, acetic acid, ethyl acetate, ethanol, and benzene.

5.0Chemical Properties of Carbon Monoxide

• Toxicity and Flammability:

Carbon monoxide is a highly poisonous and flammable gas.

• Reaction with Chlorine:

Carbon monoxide reacts with chlorine to form phosgene (COCl₂).

CO + Cl₂ → COCl₂

• Reducing Agent in Blast Furnaces:

Carbon monoxide is a reducing agent that extracts iron from its ore in blast furnaces.

Fe₂O₃ + 3CO → 2Fe + 3CO₂

• Reaction with Copper Oxide:

Carbon monoxide reacts with copper oxide to produce copper and carbon dioxide.

CuO + CO → Cu + CO₂

• Reaction with Caustic Alkalies:

Carbon monoxide reacts with caustic alkalies to form alkali formates, which can be converted into formic acid or alkali oxalates to produce oxalic acid.

• Formation of Carbonyl Compounds:

Carbon monoxide forms carbonyl compounds when it reacts with certain metals, many of which are flammable. This reaction is used to purify nickel.

 Ni + 4CO → Ni(CO)₄

• Methanol Production:

Carbon monoxide and hydrogen are the reactants used to produce methanol. These reactants are also used to create aldehydes and alcohols derived from olefins and mixtures of liquid hydrocarbons.

CO + 2H₂ → CH₃OH

• Binding with Hemoglobin:

Carbon monoxide combines with haemoglobin in the blood, forming carboxyhaemoglobin (HgbCO), which prevents oxygen transport and can be fatal in humans due to excessive intake.

Hgb + CO → HgbCO

Reaction with Water Vapour:

Carbon monoxide reacts with water at high temperatures to produce carbon dioxide and hydrogen. This reaction is used to produce hydrogen for ammonia synthesis.

CO + H₂O → CO₂ + H₂

6.0Carbon Monoxide Poisoning

Carbon monoxide (CO), when combined with haemoglobin in the blood, displaces oxygen and reduces the body's ability to transport oxygen to vital organs such as the heart and brain.

In environments with high concentrations of CO, especially indoors, carbon monoxide poisoning can occur, leading to various symptoms:

• Headaches
• Nausea and vomiting
• Dizziness
• In severe cases, coma or death with prolonged exposure

The intensity of these symptoms correlates with how long one is exposed to carbon monoxide and the inhaled gas concentration. Early detection and prompt removal from the affected environment are essential to prevent severe health outcomes.

Causes of Carbon Monoxide Poisoning

Carbon monoxide (CO) is usually not a concern in well-ventilated spaces. However, CO can accumulate quickly in relatively airtight spaces and become dangerous.

Indoor garages can be particularly hazardous. Never leave the car running in the garage, even if the garage door is open.

Other sources of dangerous carbon monoxide emissions include:

• Faulty gas stoves and appliances, including clothes dryers, space heaters, and fireplaces
• Wood-burning fireplaces
• Faulty water heaters
• Old or malfunctioning furnaces that burn gas, oil, coal, or wood
• Clogged chimneys
• Using outdoor fuel-burning or gas-powered appliances indoors
• Fires

Proper maintenance and ventilation are crucial to prevent CO buildup and ensure safety.

Treatment for Carbon Monoxide Poisoning

Carbon monoxide poisoning is treated by administering 100% oxygen to replenish oxygen levels in the blood. The method of oxygen delivery depends on the severity of the exposure:

• Mild Poisoning: Treated with oxygen delivered through a mask.
• Severe Poisoning May require a full-body, high-pressure chamber (hyperbaric oxygen therapy) to force oxygen into the body more effectively.

7.0Uses of Carbon Monoxide (CO)

The large-scale industrial production of carbon monoxide underscores its significance across various fields. These diverse applications highlight the versatility and importance of carbon monoxide in industrial and commercial processes. Some of its key uses include: