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Metallurgy Class-10 Goyal Brothers ICSE Chemistry Solutions Ch-7

Metallurgy Class-10 Goyal Brothers ICSE Chemistry Solutions Ch-7. Step by Step Solutions of Exercise and Objective Type Questions of Goyal Brothers Prakashan (A new approach to ICSE Chemistry) Chapter-7 Metallurgy for Class 10 .  Visit official Website CISCE  for detail information about ICSE Board Class-10 Chemistry .

Metallurgy Class-10 Goyal Brothers ICSE Chemistry Solutions Ch-7


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Exercise 1

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Exercise 2

Objective Type Questions


Exercise 1 Page -129

Metallurgy Class-10 Goyal Brothers ICSE Chemistry Solutions Ch-7

Question 1. Name the ore of the following metals which occur in nature as  (i) carbonates (ii) sulphides. Metals are zinc, copper and iron.

Answer :

 (i) carbonates

Carbonate Ores Calcium Limestone (CACO3)
Zinc Calamine (ZnCO3)
Iron Siderite (FeCO3)

(ii) sulphides

Sulphide Zinc Zinc blende (ZnS)
Copper Copper glance (Cu2S)
Lead Galena (PbS)
Mercury Cinnabar (HgS)

Question 2. Define the following terms: (i) minerals, (ii) ore, (ii) gangue, (iv) metallurgy.

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Answer :

 (i) minerals-A mineral is an element or chemical compound that is normally crystalline and that has been formed as a result of geological    processes””Minerals are naturally-occurring inorganic substances with a definite and predictable chemical composition and physical properties

(ii) ore- Ore is natural rock or sediment that contains one or more valuable minerals, typically metals, that can be mined, treated and sold at a profit. Ore is extracted from the earth through mining and treated or refined, often via smelting, to extract the valuable metals or minerals

(ii) Gangue – The definition of gangue is worthless rock or mineral in which valuable minerals are found. An example of gangue is the rock surrounding a deposit of gold.

 (iv) metallurgy-Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are called alloys. Metallurgy encompasses both the science and the technology of metals.

Question 3. What do you understand by the term “concentration of ore”? Name three processes used for the concentration of ores and name one specifc ore which can be concentrated by the named process.

Answer

Ores are solid material from which a pure metal can be obtained. The process of removal of unwanted material from the ore is known as concentration or dressing or benefaction of ores. It involves several steps. The separation of required material from the ore is dependent on the differences in physical properties of the compound of the metal present and that of the gangue.

Question 4. What do you understand by the terms calcination and roasting? What is their importance in the extraction of metals?

Answer :

Calcination is a process in which ore is heated in the absence of air or air might be supplied in limited quantity. Roasting involves heating of ore lower than its melting point in the presence of air or oxygen. Calcination involves thermal decomposition of carbonate ores

Question 5. Name the process used and the reducing agent employed for the extraction of

(i) aluminium from aluminium oxide,
(ii) iron from haematite,

(iii) chromium from chromium oxide. Write chemical equations in support of your answer.

Answer :

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(i) aluminium from aluminium oxide,–Aluminium ore is called bauxite . The bauxite is purified to produce aluminium oxide, a white powder from which aluminium can be extracted. The extraction is done by electrolysis. The ions in the aluminium oxide must be free to move so that electricity can pass through it.
(ii) iron from haematite,–Iron is extracted from its ore, haematite in a blast furnace. The ore is led into the top of the furnace along with coke and limestone. The limestone decomposes in the hot furnace, forming calcium oxide. This reacts with the sandy impurities (silicon dioxide) to form a slag

(iii) chromium from chromium oxide.–Chromium is generally extracted from its ores by oxidation in the form of chromate, in which state its valence is six. … The chromate in solution is acidified with sulfuric acid to form the bichromate, an intermediate product commonly used in the preparation of the various chromium derivatives

 Question 6. Name four different methods for the refining of metals. Support your answer with a specific example.

Answer :

There are several different methods that can be used for refining metals including:
  • Distillation.
  • Liquation.
  • Poling.
  • Electrolysis.
  • Zone refining.

Question 7. Give the chemical formula of the following naturally occurring ores:

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(i) cryolite, (ii) bauxite, (ii) corundum, (iv) haematite, (v) zincite, (vi) zinc blende, (vii) cinnabar, (vii) gypsum, (ix) horn silver.

Answer :

 the chemical formula of 

(i) cryolite, –Na3AlF6

(ii) bauxite, –Al2H2O4

(ii) corundum,– Al 23

 (iv) haematite,–Fe2O3

 (v) zincite, – (Zn,Mn2+)O

(vi) zinc blende,–ZnS or SZn

 (vii) cinnabar,–HgS

 (vii) gypsum, –CaSO4⋅ 2H2O.

(ix) horn silver.–Cerargyrite, also called Horn Silver, (AgCl)


Exercise 2 Page – 135

Class-10 Metallurgy Goyal Brothers ICSE Solutions Ch-7

Question 1.

(a) Name two most important ores of aluminium.
(b) How is pure alumina obtained from the ore of aluminium?
(c) Briefly describe extraction of aluminium stating clearly the cathodic and anodic reactions.
(d) Why are cryolite and fluorspar added to alumina during the extraction of aluminium?
(e) Aluminium transmission wires are preferred to copper transmission wires. Explain.

Answer :

(a) Name two most important ores of aluminium.–Bauxite,Cryolite
(b)  pure alumina obtained from the ore of aluminium–The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide) and was developed by Carl Josef Bayer. Bauxite, the most important ore of aluminium, contains only 30–60% aluminium oxide (Al2O3), the rest being a mixture of silica, various iron oxides, and titanium dioxide
(c)  extraction of aluminium stating clearly the cathodic and anodic reactions.–

he extraction of the metal from bauxite involves the three main steps.
  • Concentration of Bauxite 
Concentration of ore is done by leaching which helps in removing impurities like , etc. Bauxite is treated with  to form sodium aluminate which on further reaction with  gives pure Alumina.
  • Electrolytic reduction of Alumina 

Electrolytic reduction of pure alumina takes place in iron box (cathode) with cryolite  and fluorspar  which lowers the melting point and increases the conductivity of electrolyte. Graphide rods act as anode.

At cathode:-
At anode:- The oxygen liberated at anode reacts with the carbon of anode to produce  and .
By this process  pure aluminium is obtained


(d)  cryolite and fluorspar added to alumina during the extraction of aluminium–

Fluorspar  is added in small quantity in the electrolytic reduction of alumina dissolved in fused cryolite . Addition of cryolite and fluorspar increases the electrical conductivity of alumina and lowers the fusion temperature to around 1140 K.


(e) Aluminium transmission wires are preferred to copper transmission wires. —Aluminum is lighter that copper and is a good conductor. It has a low density and high conductivity, so it can transport current with minimal losses, while also being light enough to not need large support structures

Question 2.

(a) Give some uses of aluminium.
(b) What is thermite welding? What is the importance of thermite welding?

Answer :

(a)  some uses of aluminium.–Aluminium is a silvery-white, lightweight metal. It is soft and malleable. Aluminium is used in a huge variety of products including cans, foils, kitchen utensils, window frames, beer kegs and aeroplane parts. This is because of its particular properties

(b)  thermite welding and  importance of thermite welding

Thermit welding is an effective, highly mobile, method of joining heavy section steel structures such as rails. Essentially a casting process, the high heat input and metallurgical properties of the Thermit steel make the process ideal for welding high strength, high hardness steels such as those used for modern rails.

Question 3. Name two alloys of aluminium, stating their composition; physical properties and uses.

Answer :

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