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. a. NH₄⁺

Verified step by step guidance

1. Identify the cation in question: \( \text{NH}_4^+ \).
2. Recall that a cation can be acidic if it can donate a proton (\( \text{H}^+ \)) to water, forming \( \text{H}_3\text{O}^+ \).
3. Consider the nature of \( \text{NH}_4^+ \): it is the conjugate acid of \( \text{NH}_3 \), a weak base.
4. Since \( \text{NH}_4^+ \) can donate a proton to water, it is considered acidic.
5. Write the chemical equation showing \( \text{NH}_4^+ \) acting as an acid: \( \text{NH}_4^+ + \text{H}_2\text{O} \rightarrow \text{NH}_3 + \text{H}_3\text{O}^+ \).

Key Concepts

Acidic Cations

Acidic cations are positively charged ions that can donate protons (H+) in solution, thereby lowering the pH. These cations typically come from weak bases or are derived from the hydrolysis of metal ions. Understanding whether a cation is acidic involves recognizing its ability to interact with water and produce H+ ions.

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 is considered acidic, while a pH of 7 is neutral. The relationship between cations and pH is crucial for determining whether a cation will affect the acidity of a solution.

Hydrolysis Reactions

Hydrolysis reactions involve the reaction of a cation with water, leading to the formation of an acid and hydroxide ions. For example, when NH4+ (ammonium ion) is dissolved in water, it can donate a proton to water, forming NH3 (ammonia) and H3O+ (hydronium ion), thus demonstrating its acidic nature.