Tag: chemistry

Questions Related to chemistry

Blister copper is refined by stirring molten impure metal with green logs of wood because such a wood liberate hydrocarbon gases (like $CH {4}$). This process $X$ is called _____ and the metal contains impurities of $Y$ is ___________ .

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

  1. $X$= cupellation, $Y$= $CuO _{2}$

  2. $X$= polling, $Y$= $Cu _{2}O$

  3. $X$= polling, $Y$= $CuO$

  4. $X$= cupellation, $Y$= $CuO$

Show answer
Correct Option: B
Explanation:

The refining process of blister copper is known as polling.
The $Cu _2O$ impurities are present in the copper metal.
In presence of heat of molten metals, the green logs liberate hydrocarbon gases which reduce copper oxide into copper.

Roasting of copper pyrites is done:

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

  1. to remove moisture and volatile impurities

  2. to oxidise free sulphur

  3. to decompose pyrites into ${Cu} _{2}S$ and $FeS$

  4. to decompose ${Cu} _{2}S$ into blister copper

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

During roasting of copper pyrite ore: 

(A) moisture is removed and sulphur, arsenic and antimony are removed in the form of their volatile oxides.
(B) Free sulphur is oxidized to sulphur dioxide.
(C) Coppr pyrite decomposes into cuprous sulphide and ferrous sulphide.

Thus options A, B and C are correct.
(D) Cuprous sulphide is decomposed into blister copper during bessemerisation. 
Thus option D is incorrect.

Name the process  used for the formation of blister $Cu$ by following reaction :(unbalanced reactions)

$2Cu _2S\, +\, 3O _2\, \rightarrow\, Cu _2O\, +\, SO _2$

$Cu _2O\, +\, Cu _2S\, \rightarrow\, Cu\, +\, SO _2$ 

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

  1. Bessemerisation

  2. Parkes or Pattinson process

  3. Forth flotation

  4. None of these

Show answer
Correct Option: A
Explanation:

The process is called bessemerisation.  $Cu$ produced by Bessemerisation is known as blister $Cu$ which is $95 $%  pure. The balanced chemical reactions are as shown.

$2Cu _2S\, +\, 3O _2\, \rightarrow\, 2Cu _2O\, +\, 2SO _2$

$2Cu _2O\, +\, Cu _2S\, \rightarrow\, 6Cu\, +\, SO _2$

In the extraction of Cu, the reaction takes place in bessemer converter is:

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

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

  2. $2CuFeS _2\, +\, O _2\, \rightarrow\, Cu _2S\, +\, FeS\, +\, SO _2$

  3. $2Cu _2S\, +\, 3O _2\, \rightarrow\, 2Cu _2O\, +\,2SO _2$

  4. $2FeS\, +\, 3O _2\, \rightarrow\, 2FeO\, +\, 2SO _2$

Show answer
Correct Option: A,C
Explanation:

The sulphide ore of copper is heated in the air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged sulphide.


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

$2Cu _2S+3O _2 \rightarrow 2Cu _2O + 2SO _2$
$2Cu _2O+Cu _2S \rightarrow 6Cu+SO _2$

The final step for the extraction of copper pyrites in Bessemer converter involves the reaction__________.

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

  1. $Cu _2S\,+\,2FeO\,\rightarrow\,2Cu\,+\,2Fe\,+\,SO _2$

  2. $Cu _2S\,+\,2Cu _2O\,\rightarrow\,6Cu\,+\,SO _2$

  3. $4Cu _2O\,+\,FeS\,\rightarrow\,8Cu\,+\,2FeSO _4$

  4. $2Cu _2O\,+\,FeS\,\rightarrow\,4Cu\,+\,Fe\,+\,SO _2$

Show answer
Correct Option: B
Explanation:

The sulphide ore of copper is heated in air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged sulphide.
Self-reduction of CuS to Cu can be carried out in either Bessemer converter or Pierce-Smith converter.
$2Cu _2S+3O-2 \rightarrow 2Cu _2O + 2SO _2$
$2Cu _2O+Cu _2S \rightarrow 6Cu+SO _2$
This is the final step in Bessemer converter.

Copper matte contains:

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

  1. $Cu _2S, Cu _2O$ and silica

  2. $Cu _2S, CuO$ and silica

  3. $Cu _2S, FeO$ and silica

  4. $Cu _2S, FeS$ and silica

Show answer
Correct Option: D
Explanation:

Copper matte contains Copper Sulphide $Cu _2S$, iron sulphide $(FeS)$ with some amount of silica.


So, option D 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. Blast furnace

  3. Both (A) and (B)

  4. None of these

Show answer
Correct Option: A
Explanation:

The following reaction takes place in Bessemer converter :


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

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

Which of the following statement is correct regarding Cu-extraction ?

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

  1. In the smelting step, carbon reduction takes places

  2. During roasting, $Cu _2S$ remains almost unaffected

  3. In Bessemer converter, only self reduction occurs, not slag formation

  4. Blister formed in the blister Cu is due to dissolved $CO _2$

Show answer
Correct Option: C
Explanation:
In the extraction of copper, metal is formed in the Bessemer converter due to self reduction as

${ Cu } _{ 2 }S+2{ Cu } _{ 2 }O\rightarrow 6Cu+S{ O } _{ 2 }$
So Option C is correct

Auto reduction process is used  in the extraction of :

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

  1. Cu and Pb

  2. Zn and Hg

  3. Cu and AI

  4. Fe and Pb

Show answer
Correct Option: A
Explanation:

Auto reduction process is used in the preparation of Cu, Hg and pb etc.

Which are less electro positive metal.

Extraction of zinc from zinc blende is achieved by:

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

  1. electrolytic reduction

  2. roasting followed by reduction with carbon

  3. roasting followed by reduction with another metal

  4. none of these

Show answer
Correct Option: B