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Homework Help: Vinegar concentraion

  1. Feb 24, 2017 #1
    1. The problem statement, all variables and given/known data
    After diluting 20.00mL of vinegar sample to 500.0 mL in a volumetric flask, a student titrated a 20.00 mL aliquot of this diluted solution against a 0.1120 M NaOH solution. The acetic acid requires 27.98 mL of base. What is the % HC2H3O2 in vinegar?

    2. Relevant equations
    M1V1 = M2V2

    3. The attempt at a solution
    I tried to find the concentration of vinegar when it is added to base. So M1(20.00mL) = (0.1120 M NaOH)(27.98 mL). But I have no idea how I am supposed to find the mass %. Do I have to apply the formula to get to the M before its dilution and then use the density of vinegar? (Even though the density is not mentioned in the problem?).
  2. jcsd
  3. Feb 25, 2017 #2


    User Avatar

    Staff: Mentor

    You do know where this equation comes from (and when it will fail)?


    And yes, you should know the density of the initial solution. You may initially assume it is just that of a pure water (actually it is a bit higher, but not much).
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