How does a hydronium ion form in water?

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sodium sulfate — acid–base reaction Sodium sulfate, also called Glauber's salt, is, like other salts, the product of an acid-base reaction.

A hydronium ion (H₃O⁺), also known as an oxonium ion, forms in water when a hydrogen ion (a proton, H⁺) separates from an acid and interacts with water molecules.12

Because a bare proton cannot exist in isolation in aqueous solutions, it becomes strongly attached to a water molecule to form the H₃O⁺ ion. This process is a fundamental aspect of acid–base reactions, where the proton is transferred to the water molecule. Once formed, the hydronium ion is often further hydrogen-bonded to other surrounding water molecules, creating larger hydrated species represented by the formula H(H₂O)ₙ⁺. The concentration of these hydronium ions in a solution serves as the primary measure of its acidity.1234