Determine whether each cation is acidic or pH-neutral. For those cations that are acidic, write an equation that shows how the cation acts as an acid. c. Co³⁺

Verified step by step guidance

1. insert step 1: Identify the cation in question, which is \( \text{Co}^{3+} \).
2. insert step 2: Recognize that \( \text{Co}^{3+} \) is a transition metal cation with a high positive charge, which can lead to acidic behavior.
3. insert step 3: Understand that highly charged metal cations can polarize water molecules, leading to the release of \( \text{H}^+ \) ions, thus acting as acids.
4. insert step 4: Write the chemical equation showing \( \text{Co}^{3+} \) acting as an acid: \[ \text{Co}^{3+} + 6 \text{H}_2\text{O} \rightarrow [\text{Co(H}_2\text{O})_6]^{3+} \rightarrow [\text{Co(H}_2\text{O})_5\text{OH}]^{2+} + \text{H}^+ \]
5. insert step 5: Conclude that \( \text{Co}^{3+} \) is an acidic cation because it can increase the concentration of \( \text{H}^+ \) ions in solution, lowering the pH.

Key Concepts

Acidic Cations

Acidic cations are positively charged ions that can donate protons (H+) in solution, thereby lowering the pH. These cations typically arise from transition metals and can interact with water to form hydronium ions (H3O+). Understanding whether a cation is acidic involves examining its charge and the nature of its interactions with water.

Hydrolysis of Metal Ions

Hydrolysis refers to the reaction of a metal ion with water, leading to the formation of an acidic solution. When a metal cation like Co3+ is dissolved in water, it can attract water molecules, resulting in the release of protons and the formation of a complex ion. This process is crucial for determining the acidity of the cation in solution.

pH and Acidity

pH is a measure of the hydrogen ion concentration in a solution, indicating its acidity or basicity. A pH less than 7 signifies an acidic solution, while a pH of 7 is neutral. Understanding the relationship between cations and pH is essential for determining whether a cation is acidic or neutral, as acidic cations will typically lower the pH of the solution.