Tag: chemistry

Questions Related to chemistry

Aluminium and copper are extracted from their oxide and sulphide ores respectively. Which of the following is correct ? 
I. Copper is extracted by the auto reduction of copper oxide by copper sulphide.
II. Aluminium cannot be obtained by chemical reduction due to its strong affinity for oxygen.
III. In electrometallurgy of $Al$, graphite is used as cathode to avoid reoxidation of $Al$ into $Al _2O _3$ by preventing formation of $O _2$.
IV. Sulphide ores of copper are difficult to be reduced than the oxide ores.

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

  1. $I , II ,IV$

  2. $II$ and $III$

  3. $III$

  4. $II$ and $IV$

Show answer
Correct Option: A
Explanation:

In the electrometallurgy of $Al$, graphite is used as anode as oxygen being a non-metal is liberated at the anode and the reoxidation of $Al$ into $Al _2O _3$ is avoided.

Which of the following steps correctly depicts the self-reduction of $Cu _2S$ to $Cu$?

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

  1. Roasting

  2. Smelting

  3. Bessemeriztion

  4. Poling

Show answer
Correct Option: C
Explanation:

In the extraction of copper, the self-reduction reaction of Copper taking place in a Bessemer converter is as follows:


$2Cu _{2}S+3O _{2} \rightarrow 2Cu _2O+2SO _{2}$

$Cu _{2}S+2Cu _{2}O\rightarrow 6Cu+SO _{2}$ (self reduction)

Option C is correct.

Which of the following process is not involved in the commercial extraction or pure zinc?

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

  1. Froth floatation

  2. Distillation

  3. Self-reduction

  4. Rapid cooling

Show answer
Correct Option: C
Explanation:

Reduction of zinc oxide is done by carbon, not by self reduction.

STATEMENT-1: Extraction of zinc from sphalerite ore involves the roasting followed by reduction with coke.
STATEMENT-2 : Zinc can be commercially extracted by hydrometallurgy.

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

  1. STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is a correct explanation for STATEMENT-1

  2. STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is NOT a correct explanation for STATEMENT-1

  3. STATEMENT-1 is True, STATEMENT-2 is False

  4. STATEMENT-1 is False, STATEMENT-2 is True

Show answer
Correct Option: C
Explanation:

Sphalerite ((Zn,Fe)S) is a chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron.
Extraction of Zinc follows:
Roasting followed by reduction with carbon; then electro-fining of Zn.

Hydrometallurgy:
In this process, desired metal is extracted from its solution by addition of more electro positive metal.
But there are very few metals which are more electro positive than Zn so it can not be extracted by hydrometallurgy

Which of the following process(s) occur(s) during the extraction of copper from chalcopyrites?

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

  1. froth floatation

  2. roasting

  3. bessemerisation

  4. leaching

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

In the extraction of copper, following methods are used
froth floatation
roasting
smelting
bessemerisation and 
electrolytic refining

$Zn + NH _3 \quad\xrightarrow{\small{heat}} \quad ?$

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

  1. $ZnH _2 + N _2$

  2. $Zn _3N _2 + H _2$

  3. $Zn(NH _2) _2 + H _2$

  4. $[Zn(NH _3) _4]^{2+}$

Show answer
Correct Option: D
Explanation:

Zinc(II) ion forms complex ions readily.
Reaction of the process:
$Zn + xNH _3 \quad\xrightarrow{\small{red heat}} \quad Zn(NH _3) _x$
Where $x = 4$ to $6 $ 

The $Cu _{2}O$ impurity present in blister copper is removed by:

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

  1. liquation

  2. distillation

  3. poling

  4. zone refining

Show answer
Correct Option: C
Explanation:

Blister copper is refined by poling process where it removes impurity in form of $SO _2$ and $As _2O _3$.

Which of the metal can be obtained directly during the roasting of its sulphide ore?

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

  1. Cu

  2. Zn

  3. Fe

  4. Ca

Show answer
Correct Option: A
Explanation:

During the roasting of sulphide ore of Cu, $Cu _2O$ and $Cu _2S$ formed where they react with each other to produce Cu metal.

In the extraction of copper, the smelt formed in the blast furnace contains:

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

  1. $Cu _{2}S\ +$ little $FeS$

  2. $Cu _{2}S\ +$ little $FeO$

  3. $Cu _{2}O\ +$ little $FeS$

  4. $Cu _{2}O\ +$ little $FeO$

Show answer
Correct Option: A
Explanation:

In the extraction of copper, raw material used for the Bessemer converter is matte ($Cu _2S+FeS (little)$), where matte is formed in the blast furnace.

Formation of metallic copper from the sulphide ore in the commercial metallurgical process involves:

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

  1. $Cu _{2}S$ $+\frac{3}{2} O _{2}$ $\rightarrow$ $Cu _{2}O+$$SO _{2}$ ; $Cu _{2}O$+$C$ $\rightarrow$ $2Cu$+$CO$

  2. $Cu _{2}S+$ $\frac{3}{2}O _{2}$ $\rightarrow$ $Cu _{2}O+$ $SO _{2}$; $2Cu _{2}O+$ $Cu _{2}S$ $\rightarrow$ $6Cu+$$SO _{2}$

  3. $Cu _{2}S+2O _{2}\rightarrow CuSO _{4}$; $CuSO _{4} + Cu _{2}S\rightarrow 3Cu + 2SO _{2}$

  4. $Cu _{2}S+ \frac{3}{2}O _{2} \rightarrow 2Cu+ SO _{2}$ ; $Cu _{2}O+CO\rightarrow2Cu+CO _{2}$

Show answer
Correct Option: B
Explanation:

The commercial metallurgical process for the formation of metallic copper from the sulphide ore involves oxidation of $Cu _2S$ to $Cu _2O$  and auto reduction of a mixture of $Cu _2S$ and $Cu _2O$ to copper metal.

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

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