Consider the equation $\ce{H2 + H2+ -> H + H3+}$
What is the atomic structure of the $H_3^+$ ion? I understand that the H$_3^+$ ion contains 3 protons and 2 electrons. However, how many neutrons does it contain? Couldn't $H$ be any isotope of Hydrogen, so we don't necessarily know how many neutrons?
In general, will we never know the number of neutrons within a chemical equation?