Tag: thermodynamic principles of metallurgy

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

Which of these compounds does not exist?

  1. $CuCl _2$
  2. $CuI _2$
  3. $CuF _2$
  4. $CuBr _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

  1. $Cu _2S, PbS$
  2. $PbS, HgS$
  3. $PbS, ZnS$
  4. $Ag _2S, Cu _2S$
Reveal answer Fill a bubble to check yourself
A,B Correct answer
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)
$Cu _2S+2Cu _2O\rightarrow 6Cu+SO _2$
$HgS+2HgO\rightarrow 3Hg+SO _2$ 

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

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 :

  1. II and IV

  2. III and IV

  3. I , II and IV

  4. all of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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

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

Which of the following steps are involved in hydrometallurgical process?

  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. $CuCO _3 + H _2SO _4 \longrightarrow CuSO _4 + H _2O +CO _2$
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
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) $CuCO _3 + H _2SO _4 \longrightarrow CuSO _4 + H _2O +CO _2$

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

Which of the following can be obtained by hydrometallurgy :

  1. Copper

  2. Gold

  3. Silver

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
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
Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

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

  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. $\displaystyle CuS+\frac { 3 }{ 2 } { O } _{ 2 }\longrightarrow CuO+{ SO } _{ 2 };\quad CuO+CO\longrightarrow Cu+{ CO } _{ 2 }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Thermo-metallurgical process:

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

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

Match the column I with column II and mark the appropriate choice.

Column I Column II
(A) Electrical industry (i) Zinc
(B) Batteries (ii) Steel
(C) Gutter pipes (iii) Copper
(D) Gas stove (iv) Cast iron
  1. (A) $\rightarrow$(i), (B)$\rightarrow$(ii), (C)$\rightarrow$(iii), (D) $\rightarrow$ (iv)
  2. (A) $\rightarrow$(ii), (B)$\rightarrow$(iii), (C)$\rightarrow$(iv), (D) $\rightarrow$ (i)
  3. (A) $\rightarrow$(iv), (B)$\rightarrow$(iii), (C)$\rightarrow$(ii), (D) $\rightarrow$ (i)
  4. (A) $\rightarrow$(iii), (B)$\rightarrow$(i), (C)$\rightarrow$(iv), (D) $\rightarrow$ (ii)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
A. Copper is a good conductor of electricity. So, it is used in electrical industry.
B. Batteries are made up of Zinc.
C. Cast iron is used to make Gutter pipes
D. Gas stoves are made up of steel to prevent it from rest.