Chemistry of Metals and Alloys

Silicon carbide also known as carborundum is a compound of silicon and carbon with chemical formula SiC. In manufacturing, it is used for its hardness in abrasive machining processes, such as grinding, honing, water jet cutting and sandblasting.

Chrome orange also known as chrome red is an orange pigment, which consists of lead (II) chromate and lead (II) oxide. Chrome orange can be made by precipitating lead (II) together with chromate in a basic solution or by treating chrome yellow with dye. Chrome yellow is a kind of yellow powder and is the isomorphous crystal mixture of lead chromate and lead sulphate.

The metals Iike iron, lead and copper do not burn in air. Instead they get covered with an oxide layer that is insoluble in water. When copper oxidizes it forms a very thin layer of copper oxide on the outer surface of the copper that further protects the surface from oxidation. This layer is greenish in colour and is called patina.

Copper turns green, when exposed to air due to the formation of a protective layer of copper carbonate. This protective green coating is called verdigris.

All metals are sonorous except mercury and lead. Mercury occurs in liquid state so lead is the only non sonorous metal occurring in solid state and thus exhibiting the properties of non metals.

Copper turns green when exposed to air due to the formation of a protective layer of copper carbonate called verdigris. Verdigris is a green coating or patina formed, when an alloy of copper, bronze or brass is weathered and exposed to the atmosphere or water over a long period of time. The colour of verdigris varies from shades of blue to shades of green. The simple composition of verdigris is copper carbonate and copper hydroxide,  but if verdigris is being formed at the seashore or somewhere near the sea it consists of copper chloride.

Alnico is a powerful permanent magnet alloy containing iron, nickel and aluminium. Aluminium nickel cobalt (AlNiCo) magnet alloy exhibits excellent temperature stability.

Bell metal is an alloy and consists of Cu = 80%, Sn = 20%. Wood metal consists of Bi = 50%, Pb = 25%, Sn = 12.5% & Cd = 12.5% and is used in the making of automatic sprinkles as it melts in hot water (m.p.= 68 oC). Duralumin is used in the manufacturing of aeroplane parts and consists of Al = 95.5%, Cu = 4%, Mg = 0.5% and Mn = 0.5%.

Gold leaf electroscope consists of (1) brass disc (2) rubber stopper (3) brass rod (4) gold leaf. So 3^rd option i.e. metallic rubber is not present in the gold leaf electroscope.

Gallium is a chemical element with symbol Ga and atomic number 31. Elemental gallium does not occur in nature but as gallium compounds in trace amounts in bauxite and zinc ores.

Fuse wire is traditionally made of a tin-lead alloy (63% tin, 37% lead) because this combination has a low melting point. When excessive current flows, the wire heats and melts, breaking the circuit and preventing damage to appliances or wiring.

The red color of ruby is due to the chromium oxide.

Electroplating is mostly done on iron to prevent its corrosion and also to improve the looks of the object.

The Arsenic atom in arsenate has a valency of 5 and is also known as pentavalent arsenic.

Mischmetal is an alloy of rare earth elements in various naturally occurring proportions. Rose's metal consists of 50% bismuth, 25–28% lead and 22–25% tin. Constantan is a copper-nickel alloy usually consisting of 55% copper and 45% nickel.