Which statement correctly defines Arrhenius acids?

Which statement correctly defines Arrhenius acids?

• A. A substance that provides hydrogen ions (H+) in water.
• B. A substance that provides hydroxide ions (OH-) in water.
• C. A substance that donates a proton to another species.
• D. A substance that accepts electrons.

Answer: (A)

Arrhenius acids are substances that increase the concentration of hydrogen ions in aqueous solution. In water, those H+ ions are effectively present as hydronium ions (H3O+), so the defining feature is that the substance dissociates to yield H+ (as H3O+) in water. That’s why the statement describing an acid as something that provides hydrogen ions in water is the best fit. The other ideas point to different concepts. Providing hydroxide ions in water would make a base under the Arrhenius view. Donating a proton describes the Bronsted-Lowry concept, which is related but broader than the Arrhenius definition. Accepting electrons describes a Lewis-type interaction, not the Arrhenius acid idea.

Arrhenius acids are substances that increase the concentration of hydrogen ions in aqueous solution. In water, those H+ ions are effectively present as hydronium ions (H3O+), so the defining feature is that the substance dissociates to yield H+ (as H3O+) in water. That’s why the statement describing an acid as something that provides hydrogen ions in water is the best fit.

The other ideas point to different concepts. Providing hydroxide ions in water would make a base under the Arrhenius view. Donating a proton describes the Bronsted-Lowry concept, which is related but broader than the Arrhenius definition. Accepting electrons describes a Lewis-type interaction, not the Arrhenius acid idea.