Weight percent of hypochlorite in bleach

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Discussion Overview

The discussion revolves around calculating the weight percent of hypochlorite in a bleach sample based on a titration experiment. Participants explore the relationships between the moles of thiosulfate used in the titration and the resulting calculations needed to determine the concentration of hypochlorite in the original bleach solution.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant outlines the chemical reactions involved in the titration process and expresses uncertainty about the next steps after calculating moles of thiosulfate.
  • Another participant questions whether the weight percent should be calculated based on weight/volume or weight/weight, indicating a need for clarification on the problem's requirements.
  • A third participant emphasizes the importance of balancing all reactions and suggests a systematic approach to solving the problem by working backwards from the moles of thiosulfate to the moles of hypochlorite.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the method for calculating the weight percent of hypochlorite, and there are differing interpretations regarding the basis for the weight percent calculation.

Contextual Notes

There is ambiguity regarding the definitions of weight percent (weight/volume vs. weight/weight) and the completeness of the chemical reactions involved, which may affect the calculations.

~Sam~
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Homework Statement


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?


Homework 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)

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.
 
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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?
 
chemisttree said:
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?

Based on volume, per 100 mL
 
Have you tried to answer the first question chemistree asked?
 
Last edited by a moderator:
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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