Redox Reactions: Identifying Oxidation and Reduction in Chemical Equations

Redox Reactions

Identifying Oxidation and Reduction

Redox (reduction-oxidation) reactions involve the transfer of electrons between chemical species. In these reactions, one element is oxidized (loses electrons) and another is reduced (gains electrons). Understanding how to identify which species is oxidized and which is reduced is fundamental in GOB Chemistry.

• Oxidation: The process in which an atom, ion, or molecule loses electrons. The oxidation state of the element increases.

• Reduction: The process in which an atom, ion, or molecule gains electrons. The oxidation state of the element decreases.

Example: Analyzing the Reaction

Consider the following reaction:

$2PbO(s) \rightarrow 2Pb(s) + O_2(g)$

• Assign Oxidation States:

  • In $PbO$, $Pb$ has an oxidation state of +2 and $O$ is -2.

  • In $Pb(s)$, $Pb$ is in its elemental form, so its oxidation state is 0.

  • In $O_2(g)$, $O$ is also in its elemental form, so its oxidation state is 0.

• Determine Changes:

  • $Pb$: +2 (in $PbO$) → 0 (in $Pb$) → Reduction (gain of electrons)

  • $O$: -2 (in $PbO$) → 0 (in $O_2$) → Oxidation (loss of electrons)

• Conclusion: In this reaction, oxygen is oxidized and lead is reduced.

Key Terms

• Oxidizing Agent: The substance that is reduced (gains electrons).

• Reducing Agent: The substance that is oxidized (loses electrons).

Application: Multiple Choice Analysis

Given the reaction and the answer choices:

Option	Analysis
Pb is oxidized, O is reduced	Incorrect: Pb is reduced, O is oxidized
O is oxidized, Pb is reduced	Correct: Matches the analysis above
both O and Pb are oxidized	Incorrect: Only O is oxidized
both O and Pb are reduced	Incorrect: Only Pb is reduced