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For each of the following redox equations, identify the elements undergoing oxidation and reduction. State the oxidation number of the elements on both sides of the equation and give the change in oxidation number.

1. [tex]C + O_2 \rightarrow CO_2[/tex]
2. [tex]Fe + CuCl_2 \rightarrow FeCl_2 + Cu[/tex]
3. [tex]2 H_2O \rightarrow 2 H_2 + O_2[/tex]



Answer :

Sure, let's take each chemical reaction one by one and detail the oxidation and reduction processes, the oxidation numbers of the elements involved, and the change in oxidation numbers.

### 1. [tex]\( C + O_2 \rightarrow CO_2 \)[/tex]

Identifying oxidation and reduction:

- Oxidation: An element's oxidation number increases.
- Reduction: An element's oxidation number decreases.

Oxidation States:

- Carbon (C):
- Reactant side: [tex]\( C \)[/tex] has an oxidation number of 0.
- Product side: In [tex]\( CO_2 \)[/tex], the oxidation number of carbon is +4.

Change for Carbon: [tex]\( 0 \rightarrow +4 \)[/tex].

- Oxygen (O):
- Reactant side: [tex]\( O_2 \)[/tex] (molecular oxygen) has an oxidation number of 0.
- Product side: In [tex]\( CO_2 \)[/tex], each oxygen atom has an oxidation number of -2.

Change for Oxygen: [tex]\( 0 \rightarrow -2 \)[/tex].

Summary:

- Oxidized: Carbon (its oxidation number increases from 0 to +4, indicating it loses electrons).
- Reduced: Oxygen (its oxidation number decreases from 0 to -2, indicating it gains electrons).

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### 2. [tex]\( Fe + CuCl_2 \rightarrow FeCl_2 + Cu \)[/tex]

Oxidation States:

- Iron (Fe):
- Reactant side: [tex]\( Fe \)[/tex] has an oxidation number of 0.
- Product side: In [tex]\( FeCl_2 \)[/tex], the oxidation number of iron is +2.

Change for Iron: [tex]\( 0 \rightarrow +2 \)[/tex].

- Copper (Cu):
- Reactant side: In [tex]\( CuCl_2 \)[/tex], the oxidation number of copper is +2.
- Product side: [tex]\( Cu \)[/tex] has an oxidation number of 0.

Change for Copper: [tex]\( +2 \rightarrow 0 \)[/tex].

Summary:

- Oxidized: Iron (its oxidation number increases from 0 to +2, indicating it loses electrons).
- Reduced: Copper (its oxidation number decreases from +2 to 0, indicating it gains electrons).

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### 3. [tex]\( 2 H_2O \rightarrow 2 H_2 + O_2 \)[/tex]

Oxidation States:

- Hydrogen (H):
- Reactant side: Each [tex]\( H \)[/tex] in [tex]\( H_2O \)[/tex] has an oxidation number of +1.
- Product side: In [tex]\( H_2 \)[/tex] (molecular hydrogen), the oxidation number is 0.

Change for Hydrogen: [tex]\( +1 \rightarrow 0 \)[/tex].

- Oxygen (O):
- Reactant side: Each [tex]\( O \)[/tex] in [tex]\( H_2O \)[/tex] has an oxidation number of -2.
- Product side: In [tex]\( O_2 \)[/tex] (molecular oxygen), the oxidation number is 0.

Change for Oxygen: [tex]\( -2 \rightarrow 0 \)[/tex].

Summary:

- Oxidized: Oxygen (its oxidation number increases from -2 to 0, indicating it loses electrons).
- Reduced: Hydrogen (its oxidation number decreases from +1 to 0, indicating it gains electrons).

### Consolidated Summary of Changes:

1. [tex]\( C + O_2 \rightarrow CO_2 \)[/tex]
- Carbon: 0 to +4 (oxidized)
- Oxygen: 0 to -2 (reduced)

2. [tex]\( Fe + CuCl_2 \rightarrow FeCl_2 + Cu \)[/tex]
- Iron: 0 to +2 (oxidized)
- Copper: +2 to 0 (reduced)

3. [tex]\( 2 H_2O \rightarrow 2 H_2 + O_2 \)[/tex]
- Hydrogen: +1 to 0 (reduced)
- Oxygen: -2 to 0 (oxidized)

These observations confirm which elements are undergoing oxidation and which are undergoing reduction based on their changes in oxidation numbers.