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 third reaction.

Verified step by step guidance

1. Identify the oxidation and reduction half-reactions in the given equation: \( \text{K(s)} + \text{H}_2\text{O(l)} \rightarrow \text{KOH(aq)} + \text{H}_2\text{(g)} \).
2. Write the oxidation half-reaction: Potassium (K) is oxidized to potassium hydroxide (KOH).
3. Write the reduction half-reaction: Water (H₂O) is reduced to hydrogen gas (H₂).
4. Balance the atoms in each half-reaction. For the oxidation half-reaction, balance K atoms. For the reduction half-reaction, balance H and O atoms.
5. Combine the balanced half-reactions, ensuring that the electrons lost in the oxidation half-reaction equal the electrons gained in the reduction half-reaction.

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 these reactions.

Balancing Chemical Equations

Balancing chemical equations requires ensuring that the number of atoms for each element is the same on both sides of the equation. This is achieved by adjusting coefficients in front of the compounds. For redox reactions, it often involves balancing both the mass and the charge, which can be done using half-reaction methods.

Half-Reactions

Half-reactions are used to separate the oxidation and reduction processes in a redox reaction. Each half-reaction shows the transfer of electrons and the change in oxidation states for the species involved. By balancing the half-reactions individually and then combining them, one can achieve a balanced overall reaction.