Coke
Summary: Coke is a form of carbon produced by heating coal in the absence of air. In the blast furnace, coke serves two purposes: as a fuel (burns to produce heat) and as the source of the reducing agent carbon monoxide. Tags: igcse chemistry definition metals extraction Created: 2026-07-14 Last Updated: 2026-07-23
Coke is a porous, high-carbon solid produced by heating coal in the absence of air (destructive distillation). It is almost pure carbon and is a vital raw material in the blast furnace for iron extraction.
Role in the Blast Furnace
Coke serves two essential functions:
1. Fuel — Produces Heat
C(s) + O₂(g) → CO₂(g)
Hot air is blasted into the furnace from the bottom. Coke burns in this air, releasing large amounts of heat (the reaction is highly exothermic). This heat:
- Maintains the furnace temperature at ~1500°C
- Keeps the iron and slag in molten state
2. Source of Reducing Agent
CO₂(g) + C(s) → 2CO(g)
The carbon dioxide produced from burning coke reacts with more hot coke to form carbon monoxide (CO) — the actual reducing agent that converts iron oxide to iron:
Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g)
Why Coke?
- Cheap and abundant — produced from coal
- High carbon content → efficient fuel and reducing agent
- Porous structure → allows gases to flow through
- Provides both heat AND reducing agent in one material
Key Facts
- Coke = almost pure carbon from heating coal without air
- Fuel: C + O₂ → CO₂ (provides heat)
- Reducing agent source: CO₂ + C → 2CO
- CO reduces iron oxide: Fe₂O₃ + 3CO → 2Fe + 3CO₂
- Essential raw material for the blast furnace
- Added at the top of the furnace along with hematite and limestone
See Also
This is a key term definition page — part of the IGCSE Chemistry (0620/0971) keyword glossary.