Question

The reactions which occur in blast furnace at 500 – 800 K during extraction of iron from haematite are 
 i. \(3Fe_2O_3 + CO \rightarrow 2Fe_3O_4 + CO_2\)
ii. \(Fe_2O_3 + 3C \rightarrow 2Fe + 3CO\)
iii. \(FeO + 4CO \rightarrow 3Fe + 4CO_2\)
iv. \(FeO + CO \rightarrow 2FeO + CO_2\)

• A. \( i, ii, iii, iv \)
• B. \( i, iii \text{ only} \)
• C. \( i, iv \text{ only} \)
• D. \( i, iii, iv \)

Hint:

In a blast furnace, carbon monoxide (CO) is the primary reducing agent at lower temperatures (500 – 800 K), while carbon (C) reduction occurs at much higher temperatures.

Answer 1

The Correct Option is D

The extraction of iron from haematite in a blast furnace involves multiple reactions, primarily between temperatures of 500 – 800 K. Let's examine the reactions provided:

1. \(3Fe_2O_3 + CO \rightarrow 2Fe_3O_4 + CO_2\)
2. \(Fe_2O_3 + 3C \rightarrow 2Fe + 3CO\)
3. \(FeO + 4CO \rightarrow 3Fe + 4CO_2\)
4. \(FeO + CO \rightarrow 2FeO + CO_2\)

The correct reactions relevant to the process at the specified temperatures are:

• Reaction i: This reaction occurs as iron(III) oxide reacts with carbon monoxide to form iron(II,III) oxide and carbon dioxide, fitting the temperature range.
• Reaction iii: Here, iron(II) oxide reacts with carbon monoxide to produce iron and carbon dioxide, a typical reduction step.
• Reaction iv: This reaction indicates further reduction of iron oxides with carbon monoxide, also fitting the process conditions.

Hence, the reactions occurring at 500 – 800 K during iron extraction in the blast furnace are accurately depicted by:

• \(i, iii, iv\)

Answer 2

Step 1: Understanding the Blast Furnace Reactions 
During the extraction of iron from haematite in a blast furnace at temperatures of 500 – 800 K, reduction reactions occur. Carbon monoxide (CO) acts as the reducing agent. 
Step 2: Checking the Given Reactions 
1. \(3Fe_2O_3 + CO \rightarrow 2Fe_3O_4 + CO_2\) (Occurs in blast furnace)
2. \(Fe_2O_3 + 3C \rightarrow 2Fe + 3CO\) (Direct carbon reduction does not occur at this stage)
3. \(FeO + 4CO \rightarrow 3Fe + 4CO_2\) (Reduction by CO is valid)
4. \(FeO + CO \rightarrow 2FeO + CO_2\) (Reduction step in the furnace)
Step 3: Conclusion 
Since reactions (i), (iii), and (iv) occur in the given temperature range in the blast furnace, the correct answer is: \[ \boxed{i, iii, iv} \]