Q.8E - Chemistry (OpenStax)

Question

The following reactions all occur in a blast furnace. Which of these are redox reactions?

 

\(\begin{aligned}{l}(a)3F{e_2}{O_3}(s) + CO(g) \to 2F{e_3}{O_4}(s) + C{O_2}(g)\\(b)F{e_3}{O_4}(s) + CO(g) \to 3FeO(s) + C{O_2}(g)\\(c)FeO(s) + CO(g) \to Fe(l) + C{O_2}(g)\\(d)C(s) + {O_2}(g) \to C{O_2}(g)\\(e)C(s) + C{O_2}(g) \to 2CO(g)\\(f)CaC{O_3}(s) + CaO(s) \to C{O_2}(g)\\(g)CaO(s) + Si{O_2}(s) \to CaSi{O_3}(l)\end{aligned}\)

Step-by-Step Solution

Answer

Answer is,

1. This is a redox reaction.
2. This is a redox reaction.
3. This is a redox reaction.
4. This is a redox reaction.
5. This is a redox reaction.
6. This is not a redox reaction.
7. This is not a redox reaction.

Step 1: Oxidation agent:

A redox reaction can be defined as a chemical reaction in which electrons are transferred between two reactants participating in it. It can be identified by observing the changes in the oxidation states of the reacting species.

Step 2: checking redox reaction for (a):

a)

\(3F{e_2}{O_3}(s) + CO(g) \to 2F{e_3}{O_4}(s)\)

All oxidation states of oxygen are -2

Which mean oxidation state of Fe changes from +3 to \( + \frac{8}{3}\)and C changes from +2 to +4

The redox reaction:

Oxidation: \({C^{2 + }} - 2{e^ - } \to {C^{4 + }}\)

Reduction: \(6F{e^{3 + }} + 2{e^ - } \to 6F{e^{ + \frac{8}{3}}}\)

Step 3: checking redox reaction for (b):

b)

\(F{e_3}{O_4}(s) + CO(g) \to 3FeO(s) + C{O_2}(g)\)\(\)

All oxidation states of oxygen are -2

Which mean oxidation state of Fe changes from \( + \frac{8}{3}\) to +2and C changes from +2 to +4

The redox reaction:

Oxidation: \({C^{2 + }} - 2{e^ - } \to {C^{4 + }}\)

Reduction: \(3F{e^{\frac{{98}}{3} + }} + 2{e^ - } \to 3F{e^{3 + }}\)

Step 4: checking redox reaction for (c):

c)

\(FeO(s) + CO(g) \to Fe(l) + C{O_2}(g)\)\(\)

All oxidation states of oxygen are -2

Which mean oxidation state of Fe changes from +2 to 0 and C changes from +2 to +4

The redox reaction:

Oxidation: \({C^{2 + }} - 2{e^ - } \to {C^{4 + }}\)

Reduction: \(F{e^{2 + }} + 2{e^ - } \to F{e^0}\)

Step 5: checking redox reaction for (d):

d)

\(C(s) + {O_2}(g) \to C{O_2}(g)\)\(\)

All oxidation states of c changes from 0 to +4 and of O changes from 0 to -2.

The redox reaction:

Oxidation: \({C^0} - 4{e^ - } \to {C^{4 + }}\)

Reduction: \(2{O^0} + 4{e^ - } \to 2{O^{2 - }}\)

Step 6: checking redox reaction for (e):

e)

\(C(s) + C{O_2}(g) \to 2CO(g)\)\(\)

All oxidation states of oxygen are -2

An oxidation states of c changes from 0 to +2 and from +4 to 0+2.

The redox reaction:

Oxidation: \({C^0} - 2{e^ - } \to {C^{2 + }}\)

Reduction: \({C^{4 + }} + 4{e^ - } \to {C^{2 + }}\)

Step 7: checking redox reaction for (f):

f)

\(CaC{O_3}(s) + CaO(s) \to C{O_2}(g)\)\(\)

All oxidation states of oxygen are -2 of Ca are +2 and of C are +4

This is not a redox reaction. 

Step 8: checking redox reaction for (g):

g)

\(CaO(s) + Si{O_2}(s) \to CaSi{O_3}(l)\)\(\)

All oxidation states of oxygen are -2 of Ca are +2 and of Si are +4

This is not a redox reaction.