How many milliliters of 0.200M H2SO4 will neutralize 40.0 mL of 1.50M KOH?

Let's solve this problem without using specific numbers as that's more instructive (and won't give away an answer to someone's homework problem).

The question is:
What volume Vacid of strong diprotic acid solution of molarity Macid is needed to neutralize a volume Vbase strong base solution of molarity Mbase?


So, Macid, Vbase, and Mbase are known and we are asked to find Vacid.


A strong base of the form BOH will completely dissociate in solution into B+ and OH- ions, so Mbase is the same as MOH- in this problem.


A strong diprotic acid of the form AH2 will lose both of its protons in the presence of OH- ions to form A2+ and two H+ ions, so Macid is half of MH+ in this problem.


Neutralization is the process of mixing an acidic solution with a basic solution in proportion such that the number of OH- ions in the basic solution is equal to the number of H+ ions in the acidic solution. To get the number, you must multiply the ions' molarity times there volumes.


So, we need:
MH+·Vacid = MOH-·Vbase


or


2·Macid·Vacid = Mbase·Vbase (since Macid is half of MH+ and Mbase equals MOH-)


solve for Vacid to obtain