chemistry,

in analyzing household bleach. I have a flask that contains 10.00 mL diluted bleach + 0.4g KI + 20 mL distilled water and 20 drops of 2M HCl. To that I titrated 30.60 mL Na2S2O3 and I need to calculate the number of moles of NaOCl reacted. This is what I was thinking..

Calculate volume Na2S2O3 used * molarity Na2S2O3 * balanced equation ratio. So it would look like (.03060L Na2s2O3) * (7.67*10-4 moles/L Na2S2O3)* 1 mol NOCl/2 mol Na2S2O3)

Does this look correct??

Yes, I think so; however, perhaps for the wrong reason. Perhaps you got lucky.
You titrated I2 with the S2O3^= and you omitted one factor involving I2.
2H^+ + OCl^- + 2I^- ==> I2 + Cl^- + H2O
and the titration step of
2S2O3^= + I2 ==> S4O6^= + 2I^-

so
vol S2O3^= * molarity S2O3^= x (1 mol I2/2 mols S2O3)*(1 mol OCl^-/1 mol I2) = mols OCl^-

The molarity of 7.67 x 10^-4 seems small to me but I guess you know the molarity of the thiosulfate.

check my work.

Thank you Dr.Bob. This is how I came up with the molarity of S2O3.

We used 30.60 mL of .0250M Na2S2O3 so I did .03060 L * .0250 mol/1 L. Is that not correct?

No. If you used 0.025 mol/L Na2S2O3, then 0.025 M is what goes in for molarity. You have calcualted mols Na2S2O3 which is ok but then you don't multiply by 0.03060 again.
mols NaOCl = 0.03060*0.0250*1/2 = ??

  1. 👍 0
  2. 👎 0
  3. 👁 215
asked by amy

Respond to this Question

First Name

Your Response

Similar Questions

  1. CHEMISTRY

    A solution household bleach contains 5.25% NaClO, by mass. Assuming that the density of bleach is the same as water(1.0g/ml). Calculate the volume of household bleach that should be diluted with water to make 500.0 ml of a ph=

    asked by TYLER CHIRECE on February 16, 2011
  2. Chemistry

    A solution of household bleach contains 5.25% sodium hypochlorite, NaOCl, by mass. Assuming that the density of bleach is the same as water, calculate the volume of household bleach that should be diluted with water to make 500.0

    asked by JayJay on May 29, 2013
  3. Chemistry

    A solution of household bleach contains 5.25% sodium hypochlorite, NaOCl, by mass. Assuming that the density of bleach is the same as water, calculate the volume of household bleach that should be diluted with water to make 500.0

    asked by Jematormal91 on March 23, 2012
  4. chemistry

    A solution of household bleach contains 5.25% sodium hypochlorite, NaOCl, by mass. Assuming that the density of bleach is the same as water, calculate the volume of household bleach that should be diluted with water to make 500.0

    asked by sara on April 10, 2013
  5. Chemistry

    A solution household bleach contains 5.25% NaClO, by mass. Assuming that the density of bleach is the same as water(1.0g/ml). Calculate the volume in mL of household bleach that should be diluted with water to make 500.0 ml of a

    asked by Katherine on April 20, 2012
  6. Chemistry

    A 10.0 mL volvume of Ultra Bleach is diluted in a volumetric flask. A 25.0 ml sample of this solution is analyzed accordign to the procedure in this experiment. Given that 33.75 mL of 0.135 M Na2S2O3 are needed to reach the

    asked by Ashley on January 24, 2012
  7. Chemistry Help Please

    Titration of a Sample of Household bleaches: The oxidizing agent in a household bleach is determined by placing 100 mL of distilled water in a 250 mL Erlenmeyer flask and adding 10 mL of the 10% (w/w) KI solution, swirling the

    asked by Sara on October 22, 2008
  8. Chemistry

    Then calculate the inital ClO^- concencentrations for 1st, 2nd, and 3rd reactions. Calculate [ClO^-] in a 6% bleach solution. A 6% bleach solution contains 6 grams of NaClO per 100 grams bleach. The density of 6% bleach is

    asked by Cassandra on February 28, 2012
  9. Chemistry

    Using household bleach and saltwater of the same molarity, describe the quantities of each that would me needed to make 30 ml of a solution that contained 50% of the hypochlorite in household bleach.

    asked by Sara on February 22, 2015
  10. Language Arts

    What fact does the author use to support her opinion about bleach? (1 point) 1. Bleach is a poison. 2. Bleach is an expensive part of processing water. 3. Bleach isn’t terrific to have around.

    asked by Student on February 28, 2013
  11. chemistry

    Calculate the molarity of the commercial bleach before it was diluted. bleach 6.25%

    asked by Anna on November 3, 2011

More Similar Questions