Tag: basics of metallurgy

Questions Related to basics of metallurgy

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

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

  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. $Cu _2O+\frac{1}{2}Cu _2S\rightarrow 2Cu+\frac{1}{2}SO _2$

Show answer
Correct Option: D
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.
$2Cu _2S+3O _2\rightarrow 2Cu _2O+3SO _2$
$2Cu _2O+Cu _2S\rightarrow 6Cu+ SO _2$

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].

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

  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. $[Au(CN) _4]^-, [Zn(CN) _4]^{2-}$

Show answer
Correct Option: A
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
$X={ \left[ Au{ \left( CN \right)  } _{ 2 } \right]  }^{ - }$ & $Y={ \left[ Zn{ \left( CN \right)  } _{ 4 } \right]  }^{ 2- }$

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

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

  1. concentration

  2. reduction

  3. purification

  4. all of these

Show answer
Correct Option: D
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.

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

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

  1. Sublimation

  2. Melting

  3. Condensation

  4. Evaporation

Show answer
Correct Option: B
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.

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

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

  1. Enrichment of ore

  2. Refining

  3. Magnetic separation

  4. None of the above

Show answer
Correct Option: D
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.

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

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

  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

Show answer
Correct Option: D
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.

What will happen during roasting?

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

  1. The sulphide ores are converted into oxides

  2. The oxide ores are converted into sulphides

  3. The sulphide ores are converted into carbonates

  4. The oxide ores are converted into carbonates.

Show answer
Correct Option: A
Explanation:

During roasting, the sulphide ores are converted into oxides by heating strongly in excess of air.
$ZnS + 3O _2 \rightarrow 2ZnO + 2SO _2$

Which if the following is a common reducing agent for extracting metals from ore?

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

  1. $CO$

  2. Carbon

  3. Hydrogen

  4. All of the above

Show answer
Correct Option: D
Explanation:

Reduction is the process of removal of oxygen for extraction of metals from their oxide ores. The common reducing agents used for reduction of metal oxides are: Carbon monoxide,  Carbon, Hydrogen.

During electrolysis, electrons are being added directly to the metal ions at the ___________.

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

  1. anode

  2. cathode

  3. both $A$ and $B$

  4. none of the above

Show answer
Correct Option: B
Explanation:

During electrolysis, electrons are being added directly to the metal ions at the cathode (the negative electrode). The downside (particularly in the aluminum case) is the cost of the electricity. An advantage is that it can produce very pure metals.

Which of the following technique uses high temperature to convert ore into raw metals?

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

  1. Pyrometallurgy

  2. Hydrometallurgy

  3. Both a and b

  4. None of above

Show answer
Correct Option: A
Explanation:

After the ore is mined, the metals must be extracted, usually by chemical or electrolytic reduction. Pyrometallurgy uses high temperatures  to convert ore into raw metals, while hydrometallurgy employs aqueous treatment for the same purpose.