Question

Explain the following:
A. All ores are minerals but all minerals are not ores. Justify the statement.
B. What is galvanization?
C. Give composition of brass and bronze.
D. Explain roasting with the help of reaction.
E. What do you mean by amalgam?

Answer 1

Hint: An ore is a sediment that contains one or more valuable minerals. Galvanization is a method to provide corrosion resistance. Brass and bronze, both are alloys of copper. Roasting is a method to convert a metal from its sulphide form to its oxide. The dictionary meaning of amalgam is a mixture or blend.

Complete step by step answer:
Ores are the minerals from which metals can be extracted commercially whereas all minerals cannot be used to extract any metals. For example, aluminium exists in two mineral forms - clay and bauxite. Aluminium is mainly extracted from bauxite which contains 70% aluminium oxide. Hence, bauxite is an ore of aluminium whereas clay is not ore. Therefore, all ores are minerals but all minerals need not be ores.
Galvanization is the process of applying a zinc coating on the surface of steel or iron materials. The corrosion resistant material used for this purpose is molten zinc. It is generally done to prevent the corrosion of the metals as the surface layer when comes in contact with air or moisture gets corroded.
Brass is composed of – copper and zinc whereas, bronze is composed of – copper, tin and zinc.
Roasting is the process of heating a sulfide ore in the presence of hot air. In this, sulfide is converted to its oxide and sulfur is released as sulfur dioxide.
$\text{2ZnS+3}{{\text{O}}_{\text{2}}}\to \text{2ZnO+2S}{{\text{O}}_{\text{2}}}$
Amalgam is an alloy of mercury (approx. 50%) with other metals such as -
silver-22-32%,
tin -14%
copper-8%

Note: Roasting and calcinations the methods by which concentrated ore is converted to metallic oxide. Also, Distillation, Liquation, Oxidation, Electro- refining are the processes involved in refining of ores.