USAGE OF METALS

Usage of metals

ALLOYS Alloy is a solid solution or homogeneous mixture of two or more elements at least one of which is a metal It usually has different properties than those of its components

Properties of alloys: 1. They are usually powder than pure metals 2.They are poorer conductor of electricity and heat than pure metals 3.They have high resistance to corrosion

Iron alloys: Cast iron Steel Cast iron is an alloy consisting mostly of iron with carbon from 2% to 4,5% by weight, and also Mn, Si, P and S. Cast iron harder than iron and very brittle

METAL ORES Rocks from which metals are obtained are called as ores

Extracting metals from their ores Native metals: unreactive metals like Au, Ag, Pt and Cu are found as elements The metal is obtained only by separating it from impurities, just by removing stones from soil

Extraction by removing oxygen Metal oxides are reduced by such reducing agents as C, CO, Al, or by electrolysis

Reduction by electrolysis Metals such as Na, K, Mg, Ca have to be freed from their ores by electrolytic processes, since they are active metals.

Pyrometallurgy is obtaining metals from minerals and metallurgical ores byn thermal reactions heat 2PbS + 3O 2 → 2PbO + 3SO 2 ↑ heat PbO + H 2 → Pb + H 2 O heat WO 3 + 3H 2 → W + 3H 2 O heat TiCl Mg → Ti + MgCl 2

Hydrometallurgy involves the use of aqueous solutions to extract metals or compounds from their ores. aqueous CuO + H 2 SO 4 → CuSO 4 + H 2 O CuSO 4 + Fe → FeSO 4 + Cu By this method Ag, Au, Zn, Mo obtained.