Metals and Metallurgical Processes

Field's metal has 51% In, 32.5% Bi and 16.5% Sn.

Carrolow 117 consists of 44.7% Bi, 22.6% Pb, 8.3% Sn, 19.1% In and 5.3% Cd.

P. Cuprite (Cu₂O) has 88.8% copper while chalcocite (Cu₂S) has 79.8% copper.
Q. Chalcopyrite is called blister copper. It has the chemical composition CuFeS₂. Chalcocite (Cu₂S) is an important copper ore. It is also known as redruthite or vitreous copper.
R. Goethite is a hydroxide ore of iron with the chemical formula of FeO(OH).

Prince’s metal is a type of alpha brass. Due to its yellow color, it is used as an imitation of gold. Also called Prince Rupert's metal, the alloy was named after Prince Rupert of the Rhine. The composition of prince’s metal contains 75% copper and 25% zinc.

Azurite (2CuCO₃•Cu(OH)₂) is commonly known as mountain blue or American stone.

Zincite (ZnO) is the oxide ore of zinc.

Megallium is composed of 60% cobalt, 20% chromium, 5% molybdenum, and traces of other substances.
Elinvar consists of 59% iron, 36% nickel, and 5% chromium.

A. Mild steel contains 0.15% to 0.30% of carbon. Medium steel has 0.30% to 0.60% of carbon.
B. Promoted iron is used as the catalyst in the Haber-Bosch process for the making of NH₃.
C. Mild steel is malleable and can be bent or machined. This is hardened (tempered) by heating to red heat and quenched by plunging into water or oil.

Iron pyrite (FeS₂) has a yellow metallic appearance and so it is called fool’s gold. It was mistaken for gold in the ancient times.

The ores of iron are:
Marcasite or iron pyrite (FeS₂): sulphide ore
Haematite (Fe₂O₃): oxide ore
Magnetite (Fe₃O₄): oxide ore
Orpiment (As₂S₃) is the sulphide ore of arsenic.

Cassiterite is a tin oxide mineral with the chemical formula of SnO₂. Galena is the sulphide ore of lead with chemical formula of PbS. Limonite is the hydroxide ore of iron with the chemical formula of FeO(OH). Dolomite (CaMg(CO₃)₂) is also known as dolostone. It is the carbonate mineral of Ca and Mg.
Hence, the correct answer using the codes is A - 3, B - 1, C - 4, D - 2.

P. The Parkes process, patented in 1850 uses zinc to form a material which the silver enters. This floats on the lead and can be skimmed off.
Q. The Pattinson process was patented by its inventor, Hugh Lee Pattinson, in 1833. It depended on well-known material properties; essentially that lead and silver melt at different temperatures. The equipment consisted of a row of about 8-9 iron pots, which could be heated from below. Argentiferous lead was charged to the central pot and melted. This was then allowed to cool, as the lead solidified, it was skimmed off and moved to the next pot in one direction, and the remaining metal was then transferred to the next pot in the opposite direction. The process was repeated in the pots successively, and resulted in lead accumulating in the pot at one end and silver on the other end.
R. Fire process- The initial product of copper smelting was impure black copper, which was then repeatedly melted to purify it, alternately oxidising and reducing it. In one of the melting stages, lead was added. Gold and silver preferentially dissolved in this, thus providing a means of recovering these precious metals. To produce purer copper suitable for making copper plates or hollow-ware, further melting processes were undertaken, using charcoal as fuel. The repeated application of such fire-refining processes was capable of producing copper that was 99.25% pure.

1. 18-Carat gold contains Au 75%, Ag 10 – 20% and Cu 5 – 15%.
       14-carat gold consists of Au 58%, Cu 12 – 28% and Ag 4 – 30%.
2. Sterling-S (sterling silver) alloy is composed of Ag 92.5% and Cu 7.5%.
3. The composition of Naval brass is Cu 60%, Zn 39.25% and Sn 0.75%.
4. Dow’s metal is composed of 93.8% Mg, 6% Al and 0.2% Mn.
   Hence, both statements 1 and 2 are false.

Pewter alloy is composed of 76% Sn and 24% Pb. Duralumin is composed of 94% Al, 4% Cu, and 2% Mg, Mn & Si. Dow metal contains 93.8% Mg, 6% Al, 0.2% Mn. Rose metal consists of 50% Bi, 25% Pb and 25% Sn.
Hence, the answer using the codes is A - 5, B - 1, C - 3, D - 2.

Type metal is composed of 82% Pb, 15% Sb and 3% Sn. Gun metal consists of 88% Cu, 10% Sn, 2% Zn and 0.5% Pb. Pewter alloy is composed of 76% Sn and 24% Pb. Rose metal consists of 50% Bi, 25% Pb and 25% Sn.
Hence, the correct answer using the codes is P - 3, Q - 1, R - 4, S - 2.