Question

What is [H3O+] for a 0.500 M solution of hydrochloric acid? Make sure you include the ionization equation.

Answer 1

`[H_3O^+]=0.500*mol*L^-1`

Explanation:

Strong acids (and hydrochloric acid is a strong acid), are almost completely ionized in water:

`HCl(aq) + H_2O(l) rarr H_3O^+ + Cl^-`

And thus a `0.500*mol*L^-1` solution of `HCl(aq)` is STOICHIOMETRIC in `H_3O^+` and `Cl^-`, i.e. `[H_3O^+]=[Cl^-]=0.500*mol*L^-1`.