Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
H3O+, also known as hydronium ion, is the positive ion present when an acid dissolves in water. It's responsible for the acidity of aqueous solutions.
Related terms
pH Scale: A measure of how acidic or basic water substances are. The scale ranges from 0-14; lower values indicate acidity while higher values indicate basicity.
Acid Dissociation Constant (Ka): A measure of the strength of an acid in solution; it's essentially the equilibrium constant for the dissociation reaction of an acid into its ions.
Proton Donor: In chemistry terms, this refers to acids because they donate protons (H+) to other molecules during chemical reactions.