4. Vinegar is a dilute solution of acetic acid. What is the concentration of acetic acid in the vinegar if 26.5 mL of NaOH at 0.250 M are required to neutralize 10.0 mL of vinegar?

Answer 1

How many moles NaOH did you use? That is M x L = ??
How many moles vinegar do you have in the 10 mL? Since the reaction is 1:1 (see equation below) the same number of moles of vinegar are in the 10 mL sample.
Concn = M = moles/L. So that many moles in 0.010 L = ??
CH3COOH + NaOH ==> CH3COONa + H2O