Tag: production of metals

Questions Related to production of metals

In which of the following isolations is no reducing agent required?

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. Iron from haematire

  2. Tin from tin oxide

  3. Mercury from cinnabar

  4. Zine from zinc blende

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Correct Option: C
Explanation:

Cinnabar ore is relatively concentrated, it can be processed directly without any intermediate steps to remove waste material and without requirement of a reducing agent. 

The extraction of metals from oxide ores involve(s) :

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. reduction with carbon

  2. reduction with aluminium

  3. electrolytic reduction

  4. reduction with CO

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Correct Option: A,B,C,D
Explanation:

During extraction of metals from oxide ores, the reduction of metal ore to crude metal can be carried out by using several methods such as pyrometallurgy, hydrometallurgy and electrometallurgy. Various reducing agents such as carbon, hydrogen, aluminum or other metals can be used. CO also reduces metal ores to crude metals.

$H _2$ is not widely used as the reducing agent in metallurgic process because :

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. many metals react with $H _2$ at elevated temperature forming hydrides

  2. there is a risk of explosion from $H _2$ and $O _2$ present in the air

  3. reducing power of $H _2$ does not increase with temperature

  4. reducing power of $H _2$, increases with temperature

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

$H _2$ is not widely used as the reducing agent in metallurgic process because metals react with $H _2$ at elevated temperature forming hydrides. When $H _2$ and $O _2$ present in the air are combined it will be explosive. Reducing power of $H _2$ does not increase with temperature, which is essential in metallurgy.

Lead obtained from galena ore (PbS) by air reduction or carbon reduction process contains base metal (Cu, Bi, As, Sn, Zn) as impurities. Gelatin acts as an addition agent in the electrolysis of Pb. In the presence of gelatin, Pb becomes :

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. hard and brittle

  2. soft and rubbery

  3. smooth and uniform

  4. only brittle

Show answer
Correct Option: C
Explanation:
Lead obtained contains impurities like $Cu, Sb, Sn, As, Ag, Au, etc.$ which make it hard. During electrolytic refining of lead, the electrolyte $(PbSiF _6+H _2SiF _6)$ is mixed with a little gelatin. Gelatin is added for smooth and uniform deposition of lead in this process. 

Hence, the correct option is (C).

Which of the following metal oxides are reduced by self reduction method?

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. $Cu _2O$

  2. $PbO$

  3. $HgO$

  4. $CaO$

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

Self-reduction process:  This process is also called auto reduction process or air reduction process. 


The sulphide ores of less electropositive metals like Hg, Pb, Cu etc. are heated in the air as to convert part of the ore into oxide or sulphate which then reacts with the remaining sulphide ore to give the metal and sulphur dioxide. 


No external reducing agent is used in this process.

Hence options A,B & C are correct options.

Pb is a very important element of carbon family. It forms a number of compounds which are very useful in industries. The process of removal of base metals (Cu, Sn, Bi, As) from lead is called:

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. softening process

  2. liquation

  3. parke's process

  4. cupellalion

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Correct Option: A
Explanation:

For the removal of base metals the impure bullion is charged to a softening furnace whereby oxidation these elements form drosses or slags and, with some lead, are skimmed from the bath. This is the softening process. 

Aquaregia is ___ part conc. HCI and ___ part conc. $HNO _3$.

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. one,three

  2. one,one

  3. three,three

  4. three,one

Show answer
Correct Option: D
Explanation:

Aqua regia is three parts conc. $ HCI$ and one part conc. $HNO _3$.


$HNO _3 + 3HCl \rightarrow NOCl + 2H _2O + 2CI$

So, the correct option is $D$

The main source of lead is PbS. It is converted to Pb by:- 


(i) ${PbS\xrightarrow[\Delta]{air }PbO+SO _2\xrightarrow[\Delta]{C}Pb+CO _2}$


(ii) ${PbS\xrightarrow[\Delta]{air }PbO+PbS\xrightarrow[]{\Delta}Pb+SO _2}$ 

Self reduction process is:
chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. i

  2. ii

  3. both

  4. none

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Correct Option: B
Explanation:

Self reduction process of Pb is

$PbS + 2PbO \rightarrow   3Pb + SO _2$
so (ii) is self reduction process.

Which of the following reduction processes are correct?

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. ${Fe _2O _3+C\overset{Reduction}{\rightarrow}Fe}$

  2. ${ZnO+C\overset{Reduction}{\rightarrow}Zn}$

  3. ${SnO _2+C\overset{Reduction}{\rightarrow}Sn}$

  4. ${PbO+C\overset{Reduction}{\rightarrow}Pb}$

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

Reduction is loss of oxygens.
In all the above reactions the metal oxides are reduced to metals by the elimination of oxygens,so all are reduction ractions.
Hence options A,B,C & D are correct.

Which one of the following metals can not be extracted by using Al as a reducing agent ________________.

chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

  1. $\displaystyle Na$ from $\displaystyle { Na } _{ 2 }O$

  2. $\displaystyle Cr$ from $\displaystyle { Cr } _{ 2 }{ O } _{ 3 }$

  3. $\displaystyle Mn$ from $\displaystyle { MnO } _{ 2 }$

  4. $\displaystyle Fe$ from $\displaystyle { Fe } _{ 2 }{ O } _{ 3 }$

Show answer
Correct Option: A
Explanation:

As sodium  (alkali metal) is more reactive than Al so it cannot be extracted from $Na _2O$ by using Al as a reducing agent.