Tag: basics of metallurgy

Questions Related to basics of metallurgy

$Cu _{2}S+2Cu _{2}O \rightarrow 6Cu+SO _{2}$
In which process of metallurgy of copper, above equation is involved -

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. roasting

  2. self reduction

  3. refining

  4. purification

Show answer
Correct Option: B
Explanation:

During the Bessemerisation process, the sulphide ores of less electropositive metals are heated in air to convert part of the ore into oxide or sulphate which then react with the remaining sulphide ore to give the metal and sulphur dioxide.
Copper sulphide is partially oxidised to cuprous oxide which futher can react with remaining copper sulphide to form copper and sulphur dioxide.
$2Cu _{2}S+3O _{2} \rightarrow 2Cu _{2}O+2SO _{2}$
$Cu _{2}S+2Cu _{2}O \rightarrow 6Cu+SO _{2}$
This process is also called  autoreduction process or air reduction process. 

Which of the following two substances react to produce blister copper?

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. $Cu _{2}S _{(s)}$ and $Cu _{2}O _{(s)}$

  2. $Cu _{2}O _{(s)}$ and $FeS _{(s)}$

  3. $Cu _{2}S _{(s)}$ and $O _{2(g)}$

  4. $Cu _{2}S _{(s)}$ and $FeS _{2(s)}$

Show answer
Correct Option: A
Explanation:

Blast of air converts $Cu _2S$ partly into $Cu _2O$ which reacts with remaining $Cu _2S$ to give molten copper. The copper so obtained is called "Blister copper" because, as it solidifies, $SO _2$ hidden in it escapes out producing blister on its surface

option A is correct

In the extraction of copper, the copper matte is a mixture of:

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. copper (II) sulphide and iron (II) sulphide

  2. copper (II) sulphide and iron (III) sulphide

  3. copper (I) sulphide and iron (II) sulphide

  4. copper (I) sulphide and iron (III) sulphide

Show answer
Correct Option: A
Explanation:
  • The chemical formula of copper matte is $Cu _2S+FeS$. It is a combination of copper sulphide and iron sulphide.
  • It is a phase in which extracted metal is converted into crude metal which is a final product.
  • $80-70\%$ of copper matte is used $80-95\%$. $5- 17\%$ metallic copper, $Fe-Co$ alloy etc are used.

Metallurgical process of zinc involves roasting of zinc sulphide followed by reduction. Metallic zinc distills over as it is volatile and impurities like Cu, Pd and Fe gets condensed. The crude metal obtained is called spelter, which may be purified by:

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. electrolysis process

  2. fractional distillation

  3. polling

  4. heating with iodine

Show answer
Correct Option: A,B
Explanation:

Spelter Zn is purified by both distillation and electro fining process(here we get more pure Zn).

Metal(s) which can be extracted by smelting process is/are:

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. Pb

  2. Fe

  3. Zn

  4. Al

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

Smelting is used to produce a metal from its ore. This includes iron extraction from iron ore, copper extraction, and other base metals from their ores like lead and zinc. 

Blister copper is refined by stirring molten impure metal with green logs of wood because such wood liberates hydrocarbon gases (like $CH _{4}$). Name the process involved.

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. Cupellation

  2. Poling

  3. Scaling

  4. Oxidation

Show answer
Correct Option: B
Explanation:

Blister copper contain $Cu _2O$ as impurity and is refined by poling process. 


In this process, the molten impure metal is stirred with green logs of wood because such a wood liberates hydrocarbon gases (like  $CH _{4}$), and hence, act as a reducing agent to reduce copper oxide to metal.


Option B is correct.

Self-reduction of CuS to Cu can be carried out in:

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. Bessemer converter

  2. Pierce-Smith converter

  3. both (a) and (b)

  4. None of the above

Show answer
Correct Option: C
Explanation:

Self-reduction of CuS to Cu can be carried out in either Bessemer converter or Pierce-Smith converter.
$2Cu _2S+3O-2 \rightarrow 2Cu _2O + 2SO _2$
$2Cu _2O+Cu _2S \rightarrow 6Cu+SO _2$

Which of these are spontaneous at higher temperature?

I : $2CuS\, +\, C\, \rightarrow\, 2Cu\, +\, CS _2$ 

II : $ 2CaS\, +\, C\, \rightarrow\, 2Ca\, +\, CS _2$ 

III : $ 2CuS\, +\, 3O _2\, \rightarrow\, 2CuO\, +\, 2SO _2$

Given that : $\Delta\,G^{\circ} _f$ (in $kJ$.$mol^{-1}$) for $CuS\, =\, -49$; $CS _2\, =\, 63.6$ ;  $CaS\, =\, -1320$; $CuO\, =\, -127.2$ and $SO _2\, =\, -300.4$ 

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. $2CuS\, +\, C\, \rightarrow\, 2Cu\, +\, CS _2$

  2. $ 2CaS\, +\, C\, \rightarrow\, 2Ca\, +\, CS _2$

  3. $ 2CuS\, +\, 3O _2\, \rightarrow\, 2CuO\, +\, 2SO _2$

  4. None of these

Show answer
Correct Option: A,B,C

Consider the following steps:

$CuS\,\overset{roast\,\,in\,\,air}{\rightarrow}\,(A)\, \overset{roast\,\,without\,\,air}{\rightarrow}\,(B)$

Which are the correct statements?

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. It is self-reduction

  2. It involves disproportionation: $Cu _2S\,\rightarrow\,Cu\,+\,CuS$

  3. (A) is a mixture of $Cu _2O$  and $SO _2$ and (B) is $Cu$ and $SO _2$

  4. (A) is a mixture of $Cu$ and $SO _2$ and (B) is $CuSO _4$

Show answer
Correct Option: A,C
Explanation:

Self-reduction of CuS to Cu can be carried out in either Bessemer converter or Pierce-Smith converter.

$2Cu _2S+3O _2 \rightarrow \underset {A} { 2Cu _2O + 2SO _2}$

$2Cu _2O+Cu _2S \rightarrow \underset {B} { 6Cu+SO _2}$

(A) is a mixture of $Cu _2O$  and $SO _2$ and (B) is  Cu and $SO _2$.

Lead metal is purified by electrolysis in a similar manner to copper; the electrolyte is lead (II) hexafluorosilicate $PbSiF _6$.
chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Lead metal is purified by electrolysis in a similar manner to copper, the electrolyte is Lead $(II)$ hexa Fluorosilicate $PbSiF _6$. The given statement is True.

A solution of Lead-Fluorosilicate containing an excess of fluorosilicic acid has been found to work satisfactorily as an electrolyte for refining lead.