Classify each of the following unbalanced half-reactions as either an oxidation or a reduction. (b) Pt²⁺ (aq) → Pt(s)

Verified step by step guidance

1. Identify the oxidation states of platinum in both the reactant and the product. In the reactant, Pt has an oxidation state of +2, and in the product, Pt is in its elemental form, which has an oxidation state of 0.
2. Compare the oxidation states of platinum in the reactant and the product. The oxidation state decreases from +2 in the reactant to 0 in the product.
3. Recall the definition of reduction and oxidation in terms of oxidation states. Reduction involves a decrease in oxidation state, while oxidation involves an increase.
4. Apply the definitions to the reaction. Since the oxidation state of platinum decreases, this indicates a gain of electrons.
5. Conclude that the half-reaction Pt²⁺ (aq) → Pt(s) is a reduction process because it involves a decrease in oxidation state, indicating a gain of electrons.

Key Concepts

Oxidation and Reduction

Oxidation and reduction are chemical processes that involve the transfer of electrons between species. Oxidation refers to the loss of electrons, resulting in an increase in oxidation state, while reduction involves the gain of electrons, leading to a decrease in oxidation state. These processes are always coupled, meaning that when one species is oxidized, another must be reduced.

Half-Reactions

Half-reactions are equations that show either the oxidation or reduction process separately. They are useful for balancing redox reactions and understanding the electron transfer involved. Each half-reaction includes the species undergoing oxidation or reduction, along with the electrons gained or lost, allowing for a clearer analysis of the overall reaction.

Identifying Oxidation States

Identifying oxidation states is crucial for determining whether a half-reaction is an oxidation or reduction. The oxidation state of an element in a compound indicates its degree of oxidation. In the given half-reaction, Pt²⁺ has a +2 oxidation state, while solid Pt has an oxidation state of 0, indicating that Pt²⁺ is being reduced to Pt(s) by gaining electrons.