Tag: basics of metallurgy

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

Usually refractory metals are used in construction of furances because:

  1. they are chemically inert

  2. their melting point is high

  3. they can withstand high temperature

  4. none of the above
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

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

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

  1. auto-reduction

  2. catalytic- reduction

  3. acid reduction

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Magnesium is a very reactive metal. At the high temperatures required for carbon reduction, magnesium reacts with carbon to form magnesium carbide (MgC2), making the reduction process ineffective.

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

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

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

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

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

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

  1. $ZnO, Fe _2O _3, SnO _2$
  2. $ZnO, SnO _2, MgO$
  3. $MgO, AI _2O _3$
  4. $MgO, SnO _2, Al _2O _3$,
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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:

  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
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

From the following identify the correct ones.

  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. $PbO + C \rightarrow Pb$
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
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.