Carbon Monoxide: Properties, Toxicity and Industrial Uses

Carbon monoxide has no smell, no colour, and no taste. That’s exactly what makes it so dangerous — and also why it needs its own careful chemistry.

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General Science · GenSci0022

Carbon Monoxide: Properties & Uses

Toxicity

Binds Hb 200-250x stronger than O₂

Also blocks mitochondrial cytochrome oxidase

Manufactured Gases

Water gas: steam + coke → CO + H₂

Producer gas: limited air + coke → CO + N₂

Industrial Uses

Reducing agent: iron ore, Mond nickel process

Feedstock for acetic acid, methanol synthesis

Same molecule, opposite roles

A lethal poison in a closed room is also an essential industrial reducing agent — toxicity here is about affinity for one specific protein, not the gas itself.

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Must Know

• Carbon monoxide (CO) is colourless, odourless, and tasteless, formed by the incomplete combustion of carbon-based fuels.
• CO binds haemoglobin about 200-250 times more strongly than oxygen does, forming carboxyhaemoglobin (COHb).
• Haemoglobin bound to CO can no longer carry oxygen. CO also makes the remaining haemoglobin hold onto its oxygen more tightly, worsening delivery to tissues.
• CO has a second toxic pathway too. It binds mitochondrial cytochrome c oxidase directly, blocking aerobic respiration at the cellular level.
• Industrially, CO is a key reducing agent in metallurgy, including iron-ore reduction and nickel refining via the Mond process.

Good to Know

• Water gas (CO + H₂) forms when steam passes over red-hot coke: C + H₂O → CO + H₂.
• Producer gas (mostly CO + N₂, with some CO₂) forms when a limited air supply passes over red-hot coke, a partial combustion.
• CO burns in air with a blue flame, forming carbon dioxide.
• Vehicle catalytic converters oxidise CO to CO₂, alongside reducing nitrogen oxides and burning off unburnt hydrocarbons.
• CO also serves as a feedstock for synthesising industrial chemicals, including acetic acid and methanol, via syngas-based routes.

Test Yourself

Please wait…

1. What compound does carbon monoxide form when it binds to haemoglobin?

Oxyhaemoglobin

Carboxyhaemoglobin

Methaemoglobin

Sulfhaemoglobin

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Great to Know

• CO poisoning has two separate mechanisms, not one. Blocking haemoglobin explains the immediate oxygen-delivery crisis; poisoning cytochrome oxidase explains why symptoms can linger even after oxygen therapy starts.
• The same molecule that’s lethal in a closed room is also an essential industrial reducing agent. Toxicity here is about its affinity for one specific protein, not some inherent property of the gas itself.
• Water gas and producer gas differ only in whether steam or limited air reacts with hot coke — a small change in reactant, but it produces two gases suited for very different industrial purposes.