To determine which of the following reactions is an oxidation-reduction (redox) reaction, we need to identify if there is a transfer of electrons occurring in the reaction. In redox reactions, one species is oxidized (loses electrons) and another species is reduced (gains electrons).
Let's analyze each reaction step-by-step:
1. Reaction 1:
[tex]\[
Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2
\][/tex]
In this reaction:
- Iron (Fe) in [tex]\(Fe_2O_3\)[/tex] has an oxidation state of +3. In elemental iron (Fe), the oxidation state is 0.
- Carbon (C) in [tex]\(CO\)[/tex] has an oxidation state of +2. In [tex]\(CO_2\)[/tex], carbon has an oxidation state of +4.
Reduction: [tex]\(Fe^{3+} + 3e^- \rightarrow Fe^0\)[/tex]
Oxidation: [tex]\(C^2+ \rightarrow C^4+ + 2e^-\)[/tex]
Both reduction and oxidation processes are taking place, indicating this is an oxidation-reduction reaction.
2. Reaction 2:
[tex]\[
CuSO_4 + 2NaOH \rightarrow Cu(OH)_2 + Na_2SO_4
\][/tex]
In this reaction:
- There are no changes in the oxidation states of copper, sulfur, sodium, or oxygen. All elements retain their oxidation states throughout the reaction.
- This reaction is a double displacement (metathesis) reaction, not an oxidation-reduction reaction.
3. Reaction 3:
[tex]\[
2NaOH + H_2CO_3 \rightarrow Na_2CO_3 + 2H_2O
\][/tex]
In this reaction:
- There are no changes in oxidation states of sodium, hydrogen, carbon, or oxygen.
- This reaction is an acid-base reaction, not an oxidation-reduction reaction.
4. Reaction 4:
[tex]\[
Pb(NO_3)_2 + Na_2SO_4 \rightarrow 2 NaNO_3 + PbSO_4
\][/tex]
In this reaction:
- There are no changes in the oxidation states of lead, nitrogen, sodium, or sulfur.
- This reaction is another double displacement reaction, not an oxidation-reduction reaction.
Given the above analyses, the reaction that involves a transfer of electrons and is an oxidation-reduction reaction is:
[tex]\[
Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2
\][/tex]
Thus, the correct answer is the first reaction.
