hydronium ions form when H+ ions combine with water molecules

Question

Does the hydronium ions form when H+ ions combine with water molecules?

 

Answer 1

As pointed out by Arturo, the hydronium (H3O⁺) forms by the autoionization of water molecules, but you are also correct.  When an acid is dissolved in water, you also get the formation of additional hydronium ions.

H₂O + H⁺ <==> H3O⁺

 

Answer 2

Actually, it forms when water molecules dissociate into hydronium and hydroxide ions, in chemical eqilibirium.

 

2H₂O ↔ OH^- + H₃O⁺