How many water molecules are there in a hydronium ion?

Formally, there is one. Hydronium ion is H3O+, water is H2O and comprises the following equilibrium: H3O+ = H+ + H2O From the balanced equation you can see there is only one water molecule in hydronium. read more

Configuration of Hydronium in Water. It is believed that, on average, every hydronium ion is attracted to six water molecules that are not attracted to any other hydronium ions. This topic is still currently under debate and no real answer has been found. read more

The Eigen solvation structure has the hydronium ion at the center of an H 9 O + 4 complex in which the hydronium is strongly hydrogen-bonded to three neighbouring water molecules. In the Zundel H 5 O + 2 complex the proton is shared equally by two water molecules in a symmetric hydrogen bond. read more

where there is an equilibrium between acetic acid molecules, acetate ions and hydronium ions. Mostly there are molecules of acetic acid. Water is also present in this solution, and in fact, the amount of water molecules in this and any solution greatly exceeds the amount of any solute. read more