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Determining Volume

  1. Aug 17, 2015 #1
    1. The problem statement, all variables and given/known data.
    This question is based on an experiment to determine the mass of ASA.
    Information from the experiment :
    • ASA is a weak acid with a Ka value of 3.2 x 10^-4.
    • An ASA tablet has an approximate mass of 500 g.
    • The experiment used a titration with a standardized 0.100 mol/L NaOH.

    The balanced equation is HC9H7O4(aq) + NaOH(aq) -> NaC9H7O4(aq) + H2O(l)

    a) What volume of base will you substitute into the formula when you calculate the number of moles of base used?

    2. Relevant equations.

    n=m/M

    v=n/c

    3. The attempt at the solution

    First determine molar mass of HC9H7O4
    =180.17 g/mol

    n=m/M
    =(0.500g ) / (180.17g/mol)
    =2.78 x 10^-3 mol

    v=n/c
    =(2.78 x 10^-3) / (0.1mol/L)
    =0.0278 mL
    =27.8 L

    Could someone let me know if I determined the volume of the base correctly? Thanks.

     
  2. jcsd
  3. Aug 17, 2015 #2

    Borek

    User Avatar

    Staff: Mentor

    You mixed up units in the last two lines, but - assuming you meant L first, mL second - your calculations look OK.

    But it wouldn't hurt to write more precisely what you are calculating. I am guessing you are checking what should be approximate volume of the base required to titrate ASA from a single tablet, but it doesn't necessarily follow from your post.
     
  4. Aug 17, 2015 #3
    Thanks, and sorry for my lack of clarity.
     
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