If 20 mL of .10 M H2SO4 was added to 50 mL of .10 M NaOHand the mixture was stirred, then tested with a pH meter. What is the pH?
mmoles base: 5
mmoles acid: 2
but the acid is diprotic, so you will have then 1 mmole of base in excess.
[OH]=1E-3moles/.03liters=.001/.030=3.3E-2
but [H][OH]=1E-14
then [H}]=1E-14/3.33E-2= 3E-13
pH= -log3E-13=12.5
check all this.