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

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.

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 :

(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:

(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 :

List of Aluminum Alloys

This is a list of some important aluminum or aluminium alloys.

  • Duralumin (copper, aluminum)
  • Hindalium (aluminum, magnesium, manganese, silicon)
  • Magnalium (5% magnesium)
  • Aluminum forms other complex alloys with magnesium, manganese, and platinum

Question 4. Give the common name for the carbonate ore of zinc.

Answer :

Zinc spar or Smithsonite is a carbonate ore of zinc . Its chemical formula is ZnCO

Question 5. Name two alloys which contain zinc and state their composition along with one use of each.

Answer :

Zinc is alloyed with Lead and Tin to make solder, a metal with a relatively low melting point used to join electrical components, pipes, and other metallic items. Other Zinc Alloys include Nickel Silver, typewriter metal, and German Silver. Roughly one third of all metallic Zinc produced today is used in galvanizing

Question 6.

(a) Name four important ores of iron.
(b) What objectives are achieved when the concentrated ore of iron is roasted?

Answer :

(a) Name four important ores of iron.–

  1. Haematite
  2. Magnetite
  3. Iron Pyrite
  4. Siderite

(b)

Three objectives achieved during the roasting of ores is:

1. It removes moisture from ores.

2. It makes the ore porous and more reactive.

3. It expels volatile impurities.

4. It converts sulphide ores into oxides.

Question 7. State the approximate composition and one use of the following varieties of steel :
(i) stainless steel (ii) manganese steel (iii) tungsten steel

Answer :

(i) Common Stainless Steel Products and Applications

  • Culinary uses. Kitchen sinks. Cutlery. Cookware.
  • Surgical tools and medical equipment. Hemostats. Surgical implants. …
  • Architecture (pictured above: Chrysler Building) Bridges. Monuments and sculptures.
  • Automotive and aerospace applications. Auto bodies. Rail cars

(ii) manganese steel — Manganese is used as an alloying element for many different applicationsManganese is a key component of steel.Manganese also reduces the critical cooling rate during hardening, meaning it increases the hardenability of steel. Its effect on hardenability is higher than other alloying elements

(iii) tungsten steel–Tungsten is commonly used in heavy metal alloys such as high speed steel, from which cutting tools are manufactured. It is also used in the so-called ‘superalloys’ to form wear-resistant coatings.

Question 8. Name (i) the principal metal (ii) composition (ii) one use of the following alloys:
(i) dural, (ii) magnalium, (ii) stainless steel, (iv) bronze, (v) German silver, (vi) solder, (vii) type metal, (vii) gun metal.

Answer :

(i) dural, –Duralumin is an alloy 95% aluminium, 4% copper, 0.5% manganese and 0.5% magnesium.

 (ii) magnalium,–Magnalium is an aluminium alloy with 5% magnesium and 95% aluminum.

 (ii) stainless steel,–Stainless steels are steels containing at least 10.5% chromium, less than 1.2% carbon and other alloying elements. Stainless steel’s corrosion resistance and mechanical properties can be further enhanced by adding other elements, such as nickel, molybdenum, titanium, niobium, manganese

 (iv) bronze, —Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (such as aluminium, manganese, nickel or zinc) and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon

(v) German silver,–German silver or nickel silver is an alloy of chiefly copper, zinc and nickel and is occasionally found to contain trace amounts of tin and lead. It is known for its toughness, hardness and corrosion resistance.

 (vi) solder,–Alloys commonly used for electrical soldering are 60/40 Sn-Pb, which melts at 188 °C (370 °F), and 63/37 Sn-Pb used principally in electrical/electronic work. This mixture is a eutectic alloy of these metals, which: has the lowest melting point (183 °C or 361 °F) of all the tin-lead alloys

 (vii) type metal,–Type metalalloy of lead, antimony, and tin used to make type characters for printing. By varying the proportions of the metals, the desired properties are produced for different kinds of typecasting and printing processes

 (vii) gun metal.–Gunmetal, also called G Metal, variety of bronze, formerly used for ordnance. Modern admiralty gunmetal is composed of 88 percent copper, 10 percent tin, and 2 percent zinc and is used for gears and bearings that are to be subjected to heavy loads and low speeds

Question 9. Why are alloys preferred to pure metals? Support your answer with one example.

Answer :

Alloys are, for example, generally harder than pure metals. They are made up of atoms of different sizes, rather than being uniform. This means that the layers of atoms cannot slide over each other easily, making the whole alloy much stronger than any of the pure metals that the alloy contains in isolation


Objective Type Questions Page 135 to 137

 I. Multiple Choice Questions

Class-10 Metallurgy Goyal Brothers ICSE Solutions Ch-7

Choose the correct answer from the options given below :

1. ……………………

…………………..

28.    …………….

 


 II. Fill in the blanks spaces with the choice given in brackets:

  1. ………copper…………..
  2. ……………………..
  3. ………loss…………
  4. ………basic…………
  5. ………Fe2O3………..
  6. …………Lowers……..
  7. ………..Bronze……………brass……
  8. …………..tin…………….
  9. ……………carbon…………….
  10. …………..copper…………………
  11. ……….lower…………..electrochemical series………

II. Choose from the following list, as what matches the descriptions given below.

[Minerals, metallurgy, froth floatation process, non-metals, gangue, roasting, calcination, cryolite, bauxite, calamine, thermite, haematite, german silver]
1. The compounds of metals found in nature associated with earthly impurities.-Minerals
2. The unwanted impurities such as mud, sand, etc., associated with ore.-gangue
3. The processes involved in the extraction of metals from their ores-.metallurgy,
4. Elements having oxidising properties.–non-metals
5. The process used for the concentration of sulphide ore.-froth floatation process
6. The process of heating the concentrated ore in the absence of air, such that temperature is not sufficient to melt the ore–calcination
7. The process of heating the concentrated ore in the presence of air to a high temperature.-roasting

8. An ore of aluminium.-bauxite

9. A compound of aluminium added to the alumina so as to reduce it melting point.-cryolite
10. A mixture of 3 parts of Fe2O3 and one part of powdered aluminium used for spot welding.- thermite

11. Common name of zinc ore containing ZnCO3.-calamine

12. An alloy of 50% copper, 30% zinc and 20% nickel.–german silver
13. Common name of ore containing Fe2O3—haematite

–: end of Metallurgy Solutions Goyal Brothers :–


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