Why are hydrogen ions NEVER found in an aqueous solution?

They are actually found in aqueous solutions, though they are not always written down because they form naturally. In reactions in acidic and basic equations, they are written down. The presence of hydrogen ions are actually measured by pH.

They are found with hydronium ion = H3O+

I think the proper answer is that the H^+ adds to a water molecule to form the hydronium, H3O^+ ion. Thus H3O^+ ions are found but not bare H^+.

Hydrogen ions (H+) can indeed be found in aqueous solutions, but they are typically present in very small quantities and are often quickly involved in various chemical reactions. However, the statement "hydrogen ions are NEVER found in an aqueous solution" might be misleading.

In aqueous solutions, hydrogen ions can exist due to the dissociation of acids. When an acid is dissolved in water, it can release hydrogen ions into the solution. For example, if you dissolve hydrochloric acid (HCl) in water, it dissociates into hydrogen ions (H+) and chloride ions (Cl-).

To directly observe hydrogen ions in an aqueous solution, one common method involves the use of pH indicators. These indicators change color depending on the concentration of hydrogen ions in the solution. For instance, phenolphthalein turns pink in a basic solution (low concentration of hydrogen ions) and colorless in an acidic solution (high concentration of hydrogen ions).

To summarize, while hydrogen ions can exist in aqueous solutions, their concentration is typically low and they are often involved in chemical reactions, making their direct observation challenging.