A buffer solution is prepared by mixing 15.0 mL of 2.20 M Acetic Acid and 30.0 mL of 1.55 M NaC2H3O2. ?
Determine the pH of the solution after the addition of 0.01 moles NaOH (assume there is no change in volume when the NaOH is added).
Determine the pH of the solution after the addition of 0.01 moles NaOH (assume there is no change in volume when the NaOH is added).
hcbiochem
Moles HAc = 0.0150 L X 2.20 mol/L = 0.0330 mol HAc
moles Ac- = 0.030 L X 1.55 mol/L = 0.0465
Adding 0.01 mol NaOH will quantitatively neutralize 0.0100 mol HAc forming an additional 0.0100 mol Ac-. So, after the addition:
moles HAc = 0.0230
moles Ac- = 0.0565
pH = pKa + log [Ac-]/[HAc]
pH = 4.74 + log (0.0565/0.0230)
pH = 5.13
(Note: I used actual moles of Ac- and HAc in the calculation rather than using molarities. This is find to do since a ratio of moles will equal the ratio of molarities.)