Tag: extraction of metals from ore

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

Which of the following sulphides when  heated strongly in air gives the corresponding metal without undergoing separate reduction of oxide?

  1. $Cu _2S$
  2. $FeS$
  3. $HgS$
  4. $ZnS$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$2Cu _2S+3O _2\longrightarrow 2Cu _2O+2SO _2$

$2ZnS+3O _2\longrightarrow 2ZnO+2SO _2$
$2PbS+3O _2\longrightarrow 2PbO+2SO _2$
$2HgS+3O _2\longrightarrow 2HgO+2SO _2$
$FeS+O _2\longrightarrow Fe+SO _2$
$FeS$ when heated directly in air gives $Fe$. 

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

Which of the following reactions show the process of smelting?

  1. $2PbO + PbS \rightarrow 3Pb + SO _2$
  2. $2Na[Au(CN) _2]+Zn \rightarrow Na _2[Zn(CN) _4]+2Au$
  3. $PbO+C\rightarrow Pb + CO$
  4. $2HgS + 3O _2\rightarrow 2HgO+2SO _2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Carbon reduction occurs in smelting from oxide ore. $PbO+C\longrightarrow Pb+CO$

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

Fill in the blanks with the correct choice.
The undesired impurities present in the ores are called (i). To remove the volatile impurities from the ore, the (ii) process is carried out. Flux combines with non-fusible impurities to form (iii). $CaO$ acts as a (iv) flux.

  1. (i) - gangue, (ii) -roasting, (iii) - slag, (iv) -acidic

  2. (i) - gangue, (ii) - calcination, (iii) - slag, (iv) - basic

  3. (i) - anode mud, (ii) - leaching, (iii) - matrix, (iv) -acidic

  4. (i) - gangue, (ii) -roasting, (iii) - solution, (iv) -acidic
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$(i)$ The undesired impurities present in the ores are called gangue.
$(ii)$ To remove the volatile impurities from the ore calcination is carried out.
$(iii)$ Flux combines with non-fusible impurities to form slag.
$(iv)$ $CaO$ acts as basic flux.
Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Extraction of chlorine from brine is based on:

  1. reduction

  2. displacement

  3. oxidation

  4. evaporation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
In the extraction of chlorine by electrolysis of brine, oxidation of ${ Cl }^{ - }$ ion to chlorine gas occurs.
$2{ Cl }^{ - }+2{ H } _{ 2 }O\rightarrow 2{ OH }^{ - }+{ H } _{ 2 }+{ Cl } _{ 2 }$
Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Which of the following is reactions is an example of autoreduction? 

  1. $Fe _3O _4+4CO\rightarrow 3Fe+4CO _2$
  2. $CuO+C\rightarrow 2Cu+CO$
  3. $Cu^{2+} _{(aq)}+Fe _{(s)}\rightarrow Cu _{(s)}+Fe^{(2+)} _{(aq)}$
  4. $Cu _2O+\frac{1}{2}Cu _2S\rightarrow 2Cu+\frac{1}{2}SO _2$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The sulphide ores of certain less electropositive metals like those of Hg, Pb, Cu, etc. when heated in air bring about the conversion of a part of the sulphide ore to oxide or sulphate which then reacts with the remaining sulphide to give the matal and $SO _2$. No external reducing agent is used in this process.
$2Cu _2S+3O _2\rightarrow 2Cu _2O+3SO _2$
$2Cu _2O+Cu _2S\rightarrow 6Cu+ SO _2$

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

In the process of extraction of gold, Roasted gold ore$+CN^- _{(aq)}+H _2O\overset{O _2}{\rightarrow}[X]+[OH^-]$, $[X]+Zn\rightarrow [Y]+Au$
Identify the complexes [X] and [Y].

  1. $[Au(CN) _2]^-, [Zn(CN) _4]^{2-}$
  2. $[Au(CN) _4]^{3-}, [Zn(CN) _4]^{2-}$
  3. $[Au(CN) _2]^{2-}, [Zn(CN) _6]^{4-}$
  4. $[Au(CN) _4]^-, [Zn(CN) _4]^{2-}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$4Au+8{ CN }^{ - }+2{ H } _{ 2 }O+{ O } _{ 2 }\longrightarrow 4{ \left[ Au{ \left( CN \right)  } _{ 2 } \right]  }^{ - }+4{ OH }^{ - }$
$2{ \left[ Au{ \left( CN \right)  } _{ 2 } \right]  }^{ - }+Zn\longrightarrow 2Au+{ \left[ Zn{ \left( CN \right)  } _{ 4 } \right]  }^{ 2- }$
It is Mc-Arthur process. Here
$X={ \left[ Au{ \left( CN \right)  } _{ 2 } \right]  }^{ - }$ & $Y={ \left[ Zn{ \left( CN \right)  } _{ 4 } \right]  }^{ 2- }$
Multiple choice chemistry principles of metallurgy extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

The major step involved in extraction of a metal after its ore is :

  1. concentration

  2. reduction

  3. purification

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

 The three steps involved in extraction are:
1) Concentration of the ore to remove impurities.
2) Reduction of the ore to get the metal.
3) Purification of the ore.

Multiple choice chemistry principles of metallurgy extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Which phenomenon occurs during the following change?
Solid wax left out in the sun.

  1. Sublimation

  2. Melting

  3. Condensation

  4. Evaporation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Melting (Change of solid into liquid) - The change of solid into liquid due to increase in temperature is known as melting. Ice, which is a solid melts, i.e. changes into water. 
Similarly, when solid wax gets heated it converts into liquid and this is melting process.

Multiple choice chemistry principles of metallurgy extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Which of the following is not a method of extraction of metals?

  1. Enrichment of ore

  2. Refining

  3. Magnetic separation

  4. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Refining and magnetic separation are methods of extraction of metals .Enrichment of ore is also known as concentration of ore. It means purification of ore.

Multiple choice chemistry principles of metallurgy extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Process of removal of gangue from the ore are based on:

  1. differences between physical and chemical properties of the gangue and the ore

  2. difference between densities of gangue and ore

  3. difference between melting point between of gangue and ore

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

Impurities are removed prior to the extraction of metal. The process used for removal of gangue from the ore are based on the differences between physical and chemical properties of the gangue.