Tag: basics of metallurgy

Questions Related to basics of metallurgy

Usually refractory metals are used in construction of furances because:

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

  1. they are chemically inert

  2. their melting point is high

  3. they can withstand high temperature

  4. none of the above

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Correct Option: A,C
Explanation:

The walls of a furnace should not react with metals or ore. So retractory metals are used as they are chemically inert.

Given below are the steps for extraction of copper from its ore. The balance reaction involved in reduction of copper(I) oxide with copper(I) sulphide is given in the reaction below.

      $2Cu _{2}O + Cu _{2}S \xrightarrow{Heat} 6Cu + SO _{2}$. 

This reaction is known as:

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

  1. auto-reduction

  2. catalytic- reduction

  3. acid reduction

  4. none of these

Show answer
Correct Option: A
Explanation:

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

Which of the following gases is responsible for the flame at the mouth of Bessemer converter?

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

  1. Carbon monoxide

  2. Carbon dioxide

  3. Chlorine

  4. Oxygen

Show answer
Correct Option: A
Explanation:

Carbon monoxide gas from coke is responsible for flame at the mouth of Bessemer converter, as it burns to form carbon dioxide.

Carbon cannot be used to produce magnesium by chemical reduction of $MgO$ because:

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

  1. carbon is not a powerful reducing agent

  2. magnesium reacts with carbon to form carbides

  3. magnesium is less electropositive than carbon

  4. carbon does not react with magnesium

Show answer
Correct Option: B

Which of the following metals occurs in nature principally oxide ores.

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

  1. $Ca$

  2. $Co$

  3. $Cr$

  4. $Cu$

Show answer
Correct Option: A
Explanation:
$Ca$ occurs aa calcium oxide.So the naturally occuring oreof calcium is calcium oxide $ CaO$.
Hence option A is correct.

When $FeCr _2O _4$ (chromite) is reduced with Carbon in an electric-arc furnace:

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

  1. Cr and $Fe _2O _3$ are formed

  2. Fe and $Cr _2O _3$ are formed

  3. Fe and Cr (ferrochrome) are formed

  4. $FeCrO _4$ is formed

Show answer
Correct Option: C
Explanation:

When chromite $(FeCr _2O _4)$ is reduced with carbon in an electric-arc furnace, ferrochrome (Fe and Cr) is obtained.

Carbon reduction process is not comrnerically applicable for which of the following set of oxides to extract the respective metal?
(I) ZnO  (II)$Fe _2O _3$   (III)$Al _2O _3$  (IV) $SnO _2$  (V) MgO

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

  1. $ZnO, Fe _2O _3, SnO _2$

  2. $ZnO, SnO _2, MgO$

  3. $MgO, AI _2O _3$

  4. $MgO, SnO _2, Al _2O _3$,

Show answer
Correct Option: C
Explanation:

Carbon reduction process is used to reduce less electropositive metals.
$Mg, Al$ have high electropositivity. Hence, cannot be extracted from oxides through carbon reduction process.

Carbon can be used to reduce the number of oxides and other compounds, and because of the low cost and availability of coke, this method is widely used. But the disadvantages are that:

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

  1. high temperature is needed, which is expensive

  2. many metals combine with carbon to form carbides

  3. low temperature is needed, which is expensive

  4. many metal combine with carbon and do not form carbides

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Correct Option: A,B

Metals which can be obtained by carbon reduction of their oxides are _________.

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

  1. Cu

  2. Fe

  3. Al

  4. Pb

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

 Aluminium being more electropositive than carbon, hence it is not reduced by carbon. Other metal oxides can be reduced by carbon.

From the following identify the correct ones.

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

  1. $Fe _2O _3 + 3CO \rightarrow 2Fe + 3CO _2$

  2. $ZnO + C \rightarrow Zn + CO$

  3. $Ca _3(PO _4) _2 + C \rightarrow P$

  4. $PbO + C \rightarrow Pb$

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

The correct reactions are as follows-

$Fe _2O _3+3CO\longrightarrow 2Fe+3CO _2$ in Blast furnace.
$ZnO+C\longrightarrow Zn+CO$
$PbO+C\longrightarrow Pb$
$ZnO+C$ and $PbO+C$ can be reduced with carbon.