Consider the following unbalanced oxidation-reduction reactions in aqueous solution:
Ag⁺(aq) + Li(s) → Ag(s) + Li⁺(aq)
Fe(s) + Na⁺(aq) → Fe²⁺(aq) + Na(s)
K(s) + H₂O(l) → KOH(aq) + H₂(g)
(a) Balance second reaction.

Verified step by step guidance

1. Identify the oxidation and reduction processes in the reaction: \( \text{Fe(s)} + \text{Na}^+\text{(aq)} \rightarrow \text{Fe}^{2+}\text{(aq)} + \text{Na(s)} \).
2. Determine the oxidation states of each element in the reaction. Fe goes from 0 to +2, and Na goes from +1 to 0.
3. Write the half-reactions for oxidation and reduction. Oxidation: \( \text{Fe(s)} \rightarrow \text{Fe}^{2+}\text{(aq)} + 2e^- \). Reduction: \( \text{Na}^+\text{(aq)} + e^- \rightarrow \text{Na(s)} \).
4. Balance the electrons in the half-reactions. Multiply the reduction half-reaction by 2 to balance the electrons: \( 2\text{Na}^+\text{(aq)} + 2e^- \rightarrow 2\text{Na(s)} \).
5. Combine the balanced half-reactions to form the balanced overall reaction: \( \text{Fe(s)} + 2\text{Na}^+\text{(aq)} \rightarrow \text{Fe}^{2+}\text{(aq)} + 2\text{Na(s)} \).

Key Concepts

Oxidation-Reduction Reactions

Oxidation-reduction (redox) reactions involve the transfer of electrons between species, resulting in changes in oxidation states. In these reactions, one species is oxidized (loses electrons) while another is reduced (gains electrons). Understanding the roles of oxidizing and reducing agents is crucial for balancing redox reactions.

Balancing Redox Reactions

Balancing redox reactions requires ensuring that the number of atoms and the total charge are equal on both sides of the equation. This often involves identifying half-reactions for oxidation and reduction, balancing them separately, and then combining them to form a balanced overall equation. The use of coefficients is essential to achieve this balance.

Aqueous Solutions and Ionic Compounds

In aqueous solutions, ionic compounds dissociate into their constituent ions. Understanding how these ions interact in solution is vital for predicting the products of reactions. For example, in the given reactions, recognizing the states of matter (solid, liquid, aqueous) helps in determining the solubility and reactivity of the compounds involved.