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Weight percent of hypochlorite in bleach

  1. Oct 14, 2009 #1
    1. The problem statement, all variables and given/known data
    If 5 mL of a bleach sample is diluted to 100 mL and then 30.00 mL of the dilute solution is titrated with 29.65 mL of a 0.1034 M solution of thiosulfate what is the weight percent of hypochlorite in the 5 mL of bleach?

    2. Relevant equations
    OCl−(aq) + 2I−(aq) → I2(aq) + Cl−(aq)
    First hypochlorite is reacted with idiode

    then we titrate the I2 with thiosulfate
    I2(aq) + S2O32−(aq) →I−(aq) + S4O62−(aq)

    3. The attempt at a solution

    I started by finding moles of thiosulfate and related to I2 and relate back to the hypochlorite OCl- then I used those moles to mass of the OCl- and then after that I'm not sure what to do.
  2. jcsd
  3. Oct 14, 2009 #2


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    Knowing moles can you tell us how much it (NaOCl) might weigh?

    Are you asked for a weight percent based on volume (weight/volume) or based on weight (weight/weight) of the original bleach solution?
  4. Oct 20, 2009 #3
    Based on volume, per 100 mL
  5. Oct 21, 2009 #4


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    Have you tried to answer the first question chemistree asked?
    Last edited by a moderator: Aug 13, 2013
  6. Oct 21, 2009 #5


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    Make sure all of your reactions are balanced. Start with finding the moles of thiosulfate and calculate each step backwards until you reach moles of hypochlorite. Think of the original problem description as requiring a sequence of problems to solve.
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