Tag: chemistry

Questions Related to chemistry

Which of the following methods is not involved in metallurgy of iron?

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. Calcination

  2. Smelting

  3. Concentration of ore

  4. None of these

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Correct Option: D
Explanation:
(1) Calcination is the process in which the ore is heated below its melting point, either in the absence or in a limited supply of air, in an aim to drive off volatile expunges, moisture, water of hydrates and organic matter from the ore. All ores are minerals but all minerals are not ores.

(2)Smelting is a process when a metal which is more reactive than copper needs to be extracted. For example, zinc is more reactive than copper so it has to be extracted by smelting.

(3)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.

So Calcination, Smelting, Concentration of ore all the processes used in metallurgy.

Iron is an essential nutrient for plants, which absorb it from the soil. Iron deficiency is often found in wet, clayey soils that have a high content of:

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. carbonate

  2. chloride

  3. phosphate

  4. sulphate

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Correct Option: A
Explanation:

Iron and carbon occurs combinedly. Iron ore contains carbon percentage more. In clay, wet soils carbon content is more. So, Iron deficiency is there. In reactions carbon changes to carbonate.

Iron is used in different forms, like, cast iron, steel, and alloys. The iron-carbon diagram is the basis for the branch of science known as:

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. ferrous metallurgy

  2. stereochemistry

  3. carbon metallurgy

  4. organic chemistry

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Correct Option: A
Explanation:

The percentage of Iron and Carbon determine whether it is cast Iron, Pig Iron, Steel or Alloys. Hence this is known as Ferrous Metallurgy. The main contribution is given by Iron as every type of Iron contains more than 90% of Iron.

Magnetic ceramics or ferrites contain compounds of iron. These have been used:

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. in panels for solar cells

  2. as memory elements in computers

  3. for building water-desalinators on ships

  4. for making transformers

Show answer
Correct Option: B
Explanation:

Magnetic ceramics or ferrites are used to store computer data in the residual magnetic fields of hard ferrite cores.

Which of these compounds does not exist?

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. $CuCl _2$

  2. $CuI _2$

  3. $CuF _2$

  4. $CuBr _2$

Show answer
Correct Option: B
Explanation:

Since, $CuCl _2$, $CuF _2$, $CuBr _2$ are stable and they exist but $CuI _2$ not, because Iodide ions are strong reducing agents, Therefore, copper (II) Iodide reduces to insoluble copper (I) iodide. Thus $CuI _2$ is not stable, so it does not exist in solution.

In which of the following pair(s), the minerals are converted in to metals by self-reduction process?

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. $Cu _2S, PbS$

  2. $PbS, HgS$

  3. $PbS, ZnS$

  4. $Ag _2S, Cu _2S$

Show answer
Correct Option: A,B
Explanation:

In the self reduction process, metal sulfide reacts with metal oxide to form free metal.
The conversion of metal ore to crude metal by self reduction process is carried for the pairs $Cu _2S, PbS$ and $PbS, HgS$.
For example cupric oxide reacts with cupric sulphide to form crude copper metal.
$2PbS+3O _2\rightarrow 2PbO+2SO _2$
$PbS+2PbO\rightarrow 3Pb+SO _2$ (self reduction)
$Cu _2S+2Cu _2O\rightarrow 6Cu+SO _2$
$HgS+2HgO\rightarrow 3Hg+SO _2$ 

Of the following reduction processes :

I. $Fe _2O _3\, +\, C\, \rightarrow\, Fe$        

II. $ZnO\, +\, C\, \rightarrow\, Zn$

III. $Ca _3(PO _4) _2\, +\, C\, \rightarrow\, P$

IV. $PbO\, +\, C\, \rightarrow\, Pb$

Correct processes are :

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. II and IV

  2. III and IV

  3. I , II and IV

  4. all of these

Show answer
Correct Option: D
Explanation:

The ore is reduced to metal by reduction with carbon. This is carried out during smelting. All the given four processes are correct.

Which of the following steps are involved in hydrometallurgical process?

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. $Cu _2S + 2Cu _2O \longrightarrow 6Cu + SO _2$

  2. $CuFeS _2 + 2H _2SO _4 \longrightarrow CuSO _4 + FeSO _4 + 2H _2S$

  3. $Ag _2S + 2NaCN \longrightarrow [Ag(CN) _2]^- + Na _2S$

  4. $CuCO _3 + H _2SO _4 \longrightarrow CuSO _4 + H _2O +CO _2$

Show answer
Correct Option: B,C,D
Explanation:

Hydro metallurgy is a process of extraction of metals by converting their ores into aqueous solutions of metal compounds and reduction of these solutions using suitable reducing agents.Less electropositive metals like gold and silver are extracted by this method . 
Water, dilute acids or sodium cyanide solution are used to convert the metal present in the ore into solution.
Hence, the following steps are involved in hydrometallurgical process.
(B) $CuFeS _2 + 2H _2SO _4 \longrightarrow CuSO _4 + FeSO _4 + 2H _2S$
(C) $Ag _2S + 2NaCN \longrightarrow [Ag(CN) _2]^- + Na _2S$
(D) $CuCO _3 + H _2SO _4 \longrightarrow CuSO _4 + H _2O +CO _2$

Which of the following can be obtained by hydrometallurgy :

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. Copper

  2. Gold

  3. Silver

  4. All of these

Show answer
Correct Option: D
Explanation:
Hydrometallurgy is a method for obtaining metals from their ores. It is a technique within the field of extractive metallurgy involving the use of aqueous chemistry for the recovery of metals from ores, concentrates, and recycled or residual materials.

Hydro metallurgy : (Ag, Au, Cu) –  This is wet metallurgy process. 
$Cu \rightarrow Pyro + Hydro $
$Ag$ and $Au \rightarrow$ By cynide process

Steps are : (i) Complex formation (ii) Metal displacement

Formation of metallic copper from the sulphide ore in the normal thermo-metallurgical process essentially involves which one of the following reaction? 

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. $\displaystyle CuS+\frac { 3 }{ 2 } { O } _{ 2 }\longrightarrow CuO+{ SO } _{ 2 };\quad CuO+C\longrightarrow Cu+CO$

  2. $\displaystyle CuS+\frac { 3 }{ 2 } { O } _{ 2 }\longrightarrow CuO+{ SO } _{ 2 };\quad 2CuO+CuS\longrightarrow 3Cu+{ SO } _{ 2 }$

  3. $\displaystyle CuS+{ 2O } _{ 2 }\longrightarrow { CuSO } _{ 4 };\quad { CuSO } _{ 4 }+CuS\longrightarrow 2Cu+{ 2SO } _{ 2 }$

  4. $\displaystyle CuS+\frac { 3 }{ 2 } { O } _{ 2 }\longrightarrow CuO+{ SO } _{ 2 };\quad CuO+CO\longrightarrow Cu+{ CO } _{ 2 }$

Show answer
Correct Option: B
Explanation:

Thermo-metallurgical process:

Here first sulphide ore coverts into oxide and then self reduction occurs as:
$\displaystyle CuS+\frac { 3 }{ 2 } { O } _{ 2 }\longrightarrow CuO+{ SO } _{ 2 }$
$\ 2CuO+CuS\longrightarrow 3Cu+{ SO } _{ 2 }$