How Many Moles Were Consumed in a Titration with 5.29 ml of 0.256 M Na2S2O3?

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Discussion Overview

The discussion revolves around a titration problem involving the calculation of moles of sodium thiosulfate (Na2S2O3) consumed and the moles of hypochlorite (OCl) present in a sample. Participants are attempting to solve a homework question that requires understanding of molarity, volume, and stoichiometry in the context of a chemical reaction.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant presents the overall chemical equation for the titration and attempts to calculate the moles of S2O3 consumed based on the given volume and concentration.
  • Another participant challenges the initial calculation, suggesting that the method used was incorrect and asks for clarification on the approach taken.
  • A participant realizes a mistake in the chemical equation notation and revisits the calculations, proposing a new method to find the moles of S2O3 consumed.
  • There is a discussion about the correct application of the molarity formula, with one participant asserting that they should multiply concentration by volume to find moles.
  • Another participant questions the reasoning behind multiplying by two in the context of the stoichiometry of the reaction.
  • Further clarification is sought regarding the interpretation of the stoichiometric coefficients in the balanced equation and their implications for the calculation of moles.

Areas of Agreement / Disagreement

Participants express disagreement regarding the calculations and interpretations of the stoichiometric relationships in the reaction. There is no consensus on the correct approach or final answer, as multiple interpretations and calculations are presented.

Contextual Notes

Participants' calculations depend on the correct interpretation of the chemical equation and the application of stoichiometric principles. There are unresolved issues regarding the proper use of units and the implications of the stoichiometric coefficients in the balanced equation.

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Homework Statement



The overall chemical equation for the titration reaction is:
OCl(aq) + 2 S2O3(aq) + 2H+(aq) 6 Cl(aq) + S2O6(aq) + H2O(R)

If a titration requires 5.29 ml 0.256 M Na2S2O3,
(i) how many moles of S2O32&(aq) were consumed in the titration, and
(ii) how many moles of OCl&(aq) were in the sample?


Homework Equations





The Attempt at a Solution



Ok so what i did was take .245/52.9 and multiplied it by 2 to get .0096 moles of S2O3 consumed...is that right?
 
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No.

Try to explain what you did and why.

And using numbers that were given in the question won't hurt.
 
I just realized there is supposed to be an arrow in between the 2H and the Cl; that is where the equation splits into reactants and products.

I'm looking over it again and trying something different. I messed up in the math the first go around

.256/.00529 L = 48.4 mols X 2 (because there are 2 mols S2O3) and that gives me 96.8 mols S2O3; part i

Shouldn't part (ii) just be the 48.4 mols from the previous?
 
You are still wrong. Check your units.
 
M = mols/volume

I know M and the volume, so it should be M * volume..not divided..right?

.256 * .00529 = .00135

.00135 * 2 = .0027 mols. Is that right?
 
Better, but still wrong. You got concentration&volumes&moles part right. Why do you multiply by two if you are calculating number of moles of S2O32-?
 
I multiplied by 2 because there are 2 S2O3 in the equation. Doesn't that mean you multiply it by two so that your ratio is correct?
 
Think about it - you put a mole of substance into the baker, but as reaction equation have a 2 in the equation, that means you put 2 moles in the baker? That's what you did now.
 

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