An aqueous HCl solution has a proton concentration equal to 6.00 M.  The HCl concentration in this solution is __ M?

Expert Answers
ncchemist eNotes educator| Certified Educator

We are asked to find the concentration of a solution of HCl if the resulting proton concentration is 6 M.  HCl is a strong acid.  As such, it completely ionizes into H+ (protons) and Cl-.  So every mole of protons in the solution were produced from a mole of HCl at the start.  So if we have a solution that is 6 M in protons, that means we started with a solution that was 6 M in HCl to start with.  So the answer is the HCl concentration was 6 M.