The same molecule that kills silently in a closed room is also essential in steelmaking. This article covers carbon monoxide’s properties, toxicity, and industrial uses.
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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.
✊ Must Know
Toxicity and Industrial Reduction
- The Gas ItselfCarbon monoxide (CO) is colourless, odourless, and tasteless, formed by the incomplete combustion of carbon-based fuels.
- Binding HaemoglobinCO binds haemoglobin about 200-250 times more strongly than oxygen does, forming carboxyhaemoglobin (COHb).
- Why It’s LethalHaemoglobin bound to CO can no longer carry oxygen. CO also makes the remaining haemoglobin hold onto its oxygen more tightly, worsening delivery to tissues.
- A Second PathwayCO has a second toxic pathway too. It binds mitochondrial cytochrome c oxidase directly, blocking aerobic respiration at the cellular level.
- Industrial UseIndustrially, CO is a key reducing agent in metallurgy, including iron-ore reduction and nickel refining via the Mond process.
📘 Good to Know
Water Gas, Producer Gas, and Chemical Feedstock
- Water GasWater gas (CO + H₂) forms when steam passes over red-hot coke: C + H₂O → CO + H₂.
- Producer GasProducer gas (mostly CO + N₂, with some CO₂) forms when a limited air supply passes over red-hot coke, a partial combustion.
- Burning COCO burns in air with a blue flame, forming carbon dioxide.
- Catalytic ConvertersVehicle catalytic converters oxidise CO to CO₂, alongside reducing nitrogen oxides and burning off unburnt hydrocarbons.
- Chemical FeedstockCO also serves as a feedstock for synthesising industrial chemicals, including acetic acid and methanol, via syngas-based routes.
Test Yourself
Question 1 of 1
🌟 Great to Know
Two Poisoning Mechanisms, One Molecule
- Two MechanismsCO 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.
- Same Molecule, Opposite RolesThe 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 vs. Producer GasWater 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.
📝 Exam Point of View
Exam Point of View
- NDA-NA-I 2018, Q88CO’s poisonous nature comes specifically from its ability to bind haemoglobin — not from insolubility, reducing power, or its bond structure, all real properties that aren’t the cause of toxicity. View this question on the full NDA-NA-I 2018 paper →
- NDA-NA-2 2025, Q109Water gas is CO + H₂, not to be confused with producer gas (CO + N₂) or ammonia. View this question on the full NDA-NA-2 2025 paper →
- The PatternThese questions test the precise cause behind a well-known fact (why is CO toxic, specifically?) and exact compositions of similarly-named industrial gases.
Related Topics
- GenSci0002 — Chemistry Fundamentals for Competitive Exams — the broader chemistry fundamentals (elements, compounds, acids) this article’s CO chemistry builds on.
- GenSci0003 — Biology Fundamentals for Competitive Exams — covers haemoglobin’s normal oxygen-carrying role, disrupted by CO poisoning.
- NDA-NA-2 2025 GA Paper — contains the water-gas PYQ cited above.
- Browse all General Science articles
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