If a hydrogen ion reacts with a hydroxide ion, what substance is formed?
Adding hydroxide ions to 2+ hexaaqua ions These have the form [M(H2O)6]2+. Their acidity is shown in the reaction of the hexaaqua ions with water molecules from the solution: They are acting as acids by donating hydrogen ions to water molecules in the solution.eaction of hydroxide ions with the hexaaqua ion Statistically, there is far more chance of a hydroxide ion hitting a hexaaqua metal ion than of hitting a hydrogen ion. There are far more hexaaqua ions present.