Question

72.33 mL of 0.137 M HCl was added to an Erlenmeyer flask and is titrated with 0.165 M NaOH. Calculate the pH when 5mL of NaOH is added after the equivalence point has been reached.

Answer 1

First determine L NaOH for the equivalence point.
mols excess NaOH = M NaOH x L NaOH.
New M NaOH = mols excess/total volume.
(Note: total volume = volume to reach the equivalence point + 5 mL)
That will give you the M of OH^-, then pOH = -log(OH^-) followed by
pH + pOH = pKw = 14. Solve for pH.

Answer 2

how do you determine the L NaOH?

Answer 3

MHCl x L HCl = M NaOH x L NaOH

Answer 4

mols HCl= molsNaOH?

Answer 5

yes