Tag: thermodynamic principles of metallurgy

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Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Of the following reduction processes, correct processes are :

  1. $Fe _{2}O _{3}$ + $C$ $\rightarrow$ $Fe$
  2. $ZnO$ + $C$ $\rightarrow$ $Zn$
  3. $Ca _{3}(PO _{4}) _{2}$ + $C$ $\rightarrow$ $P$
  4. $PbO$ + $C$ $\rightarrow$ $Pb$
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

(A) Carbon reduces ferric oxide to iron. $Fe _2O _3+3C \rightarrow 2Fe + 3CO$.
Thus option A is correct.
(B) Carbon reduces zinc oxide to zinc. $ZnO+C \rightarrow {\triangle} {1673  K} Zn + CO \uparrow$.
Thus option B is correct.
(C) In presence of silica, carbon reduces calcium phosphate to free phosphorus.
$2 Ca _3(PO _4) _2 + 9 SiO _2 + 16 C  \rightarrow 6 CaSiO _3 + P _4 + 16 CO$
Thus option C is correct.
(D) Carbon reduces lead oxide to lead. $2PbO+C \rightarrow 2Pb+CO _2$.
Thus option D is correct.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

The disadvantage of carbon reduction method are :

  1. high temperature needed which is expensive and requires the use of a blast furnace

  2. many metals combine with carbon forming carbides
  3. carbon combines with oxygen to form poisonous $CO$

  4. carbon cannot be used with highly electropositive metals
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

 The disadvantage of carbon reduction method are
(i) high temperature needed which is expensive and requires the use of a blast furnace
(ii) many metals combine with carbon forming carbides
(iii) carbon dioxide gas is released in the process which is green house gas.
(iii) metals produced contain significant amount of carbon. hence, metals obtained cannot be very pure.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Pyrometallurgical method used for the extraction of copper from sulphide ore:

  1. is a dry method
  2. involves concentration by leaching the sulphide ore with dil. $H _2SO _4$

  3. involves concentration of the sulphide ore by froth flotation process

  4. statement given in (b) is incorrect
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The copper is extracted from sulphide ore by pyrometallurgy which involves reduction of the concentrated ore at high temperature.
This process is a dry process.
In this process, the sulphide ore is concentrated by froth floatation process.
In this process, the sulphide ore is not concentrated by leaching with dil sulphuric acid.
Thus, the statement B is incorrect and the statement A and C are correct.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Write chemical equations for metallurgical processes to represent the reduction of $Cu _2O$ using charcoal as a reducing agent :

  1. $2Cu _2O\, +\, C\, \overset{\Delta}{\rightarrow}\, 4Cu\, +\, CO _2$
  2. $Cu _2O\, +\, C\, \overset{\Delta}{\rightarrow}\, 2Cu\, +\, CO$
  3. $3Cu _2O\, +\, 2C\, \overset{\Delta}{\rightarrow}\, 6Cu\, +\, CO +\, CO _2$

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Chemical equations for reduction of $Cu _2O$ using charcoal as a reducing agent : 

$Cu _2O\, +\, C\, \overset{\Delta}{\rightarrow}\, 2Cu\, +\, CO$.

This process is carbon reduction.


Hence option B is correct.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Chemical reactions of the hydrometallurgical extraction of copper is/are?

  1. $CuO\, +\, H _2SO _4\, \rightarrow\, CuSO _4\, +\, H _2O$
  2. $CuCO _3\, +\, H _2SO _4\, \rightarrow\, CuSO _4\, +\, H _2O\, +\, CO _2$
  3. $Cu _2S\, +\, 2H _2SO _4\, +\, 2O _2\, \rightarrow\, 2CuSO _4\, +\, SO _2\, +\, 2H _2O$

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

Hydrometallurgical extraction of copper involves leaching copper ores with sulfuric acid to produce copper sulfate solution, which is then processed to recover copper. All the listed reactions represent valid leaching processes for different copper ores.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Of the following reduction processes, correct processes are:

  1. $Fe _2O _3\,+\,C\,\rightarrow\,Fe$
  2. $ZnO\,+\,C\,\rightarrow\,Zn$
  3. $Ca _3(PO _4) _2\,+\,C\,\rightarrow\,P$
  4. $PbO\,+\,C\,\rightarrow\,Pb$
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

All the four processes are correct.
$ZnO+C\overset{1100^{0}C}{\rightarrow}Zn+CO$
$Fe _{2}O _{3}+3C\rightarrow 2Fe+3CO$
$Ca _3(PO _4) _2\,+\,C\,\rightarrow\,2P +3CaO + CO _2$
$PbO\,+\,C\,\rightarrow\,Pb +CO$

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

$AgCl$ (horn silver) is converted into $Ag$ by the pyrometallurgical method.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pyrometallurgy is the process of extraction and purification involving the application of heat.

By this process chloride residues are smelted with an agent such as sodium silicate that provides alkali  metal oxide without generating gases, such as $CO _2$.
$2AgCl+Na _2O+SiO _2\longrightarrow Ag _2O+2NaCl+SiO _2$
$Ag _2O\longrightarrow 2Ag+\cfrac {1}{2}O _2$.