chemistry
posted by ibob .
What is the pH of the solution created by combining 2.80 mL of the 0.10 M NaOH(aq) with 8.00 mL of the 0.10 M HC2H3O2(aq)?
I got 1.3. is that correct?

STEP 1: STOICHIOMETRY to find moles C2H3O2 formed and HC2H3O2 remaining. All NaOH was used up, so that's how many moles reacted with the HC2H3O2 and also how many moles C2H3O2 formed.
STEP 2: EQUILIBRIUM of HC2H3O2 with H+ and C2H3O2. Change the moles of HC2H3O2 and C2H3O2 into molarities by dividing by the TOTAL VOLUME (0.00280 L + .008L = .01080 L) and plug those into the equilibrium equation. (The value of K for HC2H3O2, or acetic acid, is 1.8 X 10 ^5)
STEP 3: SOLVE FOR pH
SUMMARY: NaOH is a strong base  Stoichiometry
Acetic acid is a weak acid  Equilibrium
Use the equilibrium equation to solve for [H+], then the pH 
No, 1.3 is not the answer. Follows Bill's instructions OR use the HendersonHasselbalch equation.