Question

Identify the reaction that does not take place in a blast furnace.
(A) \[CaC{O_3} \to CaO + C{O_2}\]
(B) \[CaO + Si{O_2} \to CaSi{O_3}\]
(C) \[2F{e_2}{O_3} + 3C \to 4Fe + 3C{O_2}\]
(D) \[C{O_2} + C \to 2CO\]

Answer 1

Hint:
In Blast Furnace, Iron is obtained by step-by-step reduction of Iron in ore giving metallic Iron in the end. Several side reactions like Combustion of Coke in presence of atmospheric oxygen, formation of some non-useful solid materials occur in the blast furnace.

Complete step-by-step answer:
In Extraction of Iron, Blast furnace is fed with Ore, Coke and Limestone form its top. Blast of very hot air is supplied from the bottom of the furnace. So, Coke will undergo combustion reaction as it is a fuel and the Carbon dioxide produced will also react with Coke. Reaction is given as under.
\[\mathop C\limits_{Coke} + {O_2} \to C{O_2}\]
\[C{O_2} + C \to 2CO\](Occur at 900-1500K)
Limestone also gets converted into Calcium oxide and Carbon dioxide gas.
\[CaC{O_3} \to CaO + C{O_2}\]
Calcium oxide reacts with Silica to give Calcium Silicate which is not a desired product and it is also called Slag. And this process is called slag formation.
\[CaO + Si{O_2} \to CaSi{O_3}\]
So, we have seen that reactions given in option (A), (B) and (D) occur in the blast furnace.
So, the correct answer is option (C) \[2F{e_2}{O_3} + 3C \to 4Fe + 3C{O_2}\].

Additional Information:
We know that Iron oxides get reduced to metallic Iron in Blast furnace but it involves step-by-step reduction of Iron at specific temperatures. Reactions are as shown Below.
\[3F{e_2}{O_3} + CO \to 2F{e_3}{O_4} + C{O_2}\](At 500-800K)
\[F{e_2}{O_3} + CO \to 2FeO + C{O_2}\](At 500-800K)
\[F{e_3}{O_4} + 4CO \to 3Fe + 4C{O_2}\](At 500-800K)
\[FeO + CO \to Fe + C{O_2}\](At 900-1500K)
\[FeO + C \to Fe + CO\] (At 900-1500K)
So, direct reduction of \[F{e_2}{O_3}\] to \[Fe\] does not occur in the Blast furnace.

Note:
- Side reactions like Combustion and slag formation take place in Blast furnace, so we also need to be considered. \[F{e_2}{O_3}\] is not reduced directly to \[Fe\] as it has a higher percentage of Oxygen in its composition.