1) Why is limestone added to the blast furnace in the extraction of iron from haemalite?
2) Explain why Aluminium is more reactive than iron, but there is less corrosion of aluminium when exposed to air.
2007-08-23 03:34:18 · 3 answers · asked by Akilesh - Internet Undertaker 7 in Science & Mathematics ➔ Chemistry
CaCO3 decomposes at high temperature to form CaO, which then reacts with SiO2 impurities in the iron ore to form a slag.
Al2O3 protects the Al underneath it against further corrosion, unlike Fe2O3.
2007-08-23 03:52:53 · answer #1 · answered by Gervald F 7 · 1⤊ 0⤋
1) To supply CaO which forms slag with SiO2 and CO2 which becomes CO on combining with C.
2) Al has a lower IP than Fe and hence is more reactive. When Al is exposed to air a tough film of Al2O3 forms on the surface which prevents further corrosion.
2007-08-23 04:03:01 · answer #2 · answered by ag_iitkgp 7 · 2⤊ 0⤋
1) it is used as a flux and is removed as calcium silicate
2) Al forms a coating of its oxide which remains stuck on the surface unlike iron there fore it prevents further corrosion
2007-08-23 03:48:11 · answer #3 · answered by Anonymous · 3⤊ 0⤋