Advanced Placement (AP) Chemistry Practice Exam

Which type of acids can ionize in water to produce hydrogen ions?

1. Brønsted-Lowry acids

2. Arrhenius acids

3. Lewis acids

4. None of the above

The correct answer is: Arrhenius acids

The correct response is Arrhenius acids, as these acids are specifically defined by their ability to produce hydrogen ions (H⁺) when dissolved in water. The Arrhenius definition identifies acids as substances that, when in aqueous solution, increase the concentration of H⁺ ions. This is a fundamental characteristic of Arrhenius acids, making them straightforward in terms of their behavior in water. Brønsted-Lowry acids, while also capable of releasing hydrogen ions, are defined based on their ability to donate protons to a base, and this definition is broader as it encompasses acid-base reactions that might not occur in water. For example, a Brønsted-Lowry acid might function in a non-aqueous solution, which doesn't align with the specific context of the question regarding ionization in water. Lewis acids are defined by their ability to accept an electron pair during a chemical reaction, which does not inherently involve the release of hydrogen ions in aqueous solutions. Therefore, while Lewis acids and Brønsted-Lowry acids can engage in proton donation or acceptance in various contexts, Arrhenius acids are singularly characterized by their contribution to H⁺ ion concentration in water, making this choice the most accurate in the