Iron is a chemical element, having the chemical symbol Fe (from the Latin ferrum). It has the atomic number (number of protons) 26 and its standard atomic weight is 55.845 g•mol −1 Pure iron is a grayish metal, lustrous, hard and brittle. It rusts (oxidizes) easily in moist air. It is attracted by a magnet and can become magnetized (is ferromagnetic). Iron is the fourth most abundant element, comprising 5% of the earth's crust. Pure iron is rare in nature, but its oxides, iron ores, are widely distributed.
Iron is prepared industrially in blast furnaces. In a blast furnace, iron ore and coke (degassed coal, which is pure carbon) are fed into the top of the furnace, while air, containing oxygen, is forced into the furnace at the bottom. In the furnace the coke reacts with oxygen:
- 2 C + O2 → 2 CO
The carbon monoxide (CO) reduces the iron oxide in the ore, giving pure iron:
- 3 CO + Fe2O3 → 2 Fe + 3 CO2
At the temperature of this process the iron is molten and flows to the bottom of the furnace where it is drained off. The resulting iron is pig iron, characterized by a relatively high (3-4%) carbon content.