J.R. S. answered 06/23/22
Ph.D. University Professor with 10+ years Tutoring Experience
HC2H3O2(aq) + KOH(aq) ==> H2O(l) + HC2H3O2(aq)
mols KOH used = 28.6 ml x 1 L / 1000 ml x 0.164 mol/L = 0.00469 mols KOH
mols HC2H3O2 present = 0.00469 mol KOH x 1 mol HC2H3O2 / mol KOH = 0.00469 mols HC2H3O2
molarity of HC2H3O2 = 0.00469 mols / 25.2 ml x 1000 ml / L = 0.186 M