How to Calculate Initial Molarity of S2O32- in a Trial

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Discussion Overview

The discussion revolves around calculating the initial molarity of the thiosulfate ion (S2O32-) in a series of trials, given specific concentrations and volumes of sodium thiosulfate (Na2S2O3). The scope includes homework-related queries and attempts to solve a molarity calculation problem.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Exploratory

Main Points Raised

  • One participant states the need to calculate the initial molarity of S2O32- based on a provided concentration and volume.
  • Another participant suggests using the definition of molarity and calculating the ratio of moles to volume.
  • There is a clarification about the total volume of 7.00 mL being the volume of the finished solution in each trial.
  • Some participants express confusion about the number of moles available and how to derive the molarity from the given data.
  • One participant mentions calculating the grams of Na2S2O3 but remains uncertain about deriving the molarity of S2O3.

Areas of Agreement / Disagreement

Participants generally agree on the need to calculate the molarity based on the provided information, but there is no consensus on the specific steps to take or the interpretation of the data. Multiple viewpoints on how to approach the problem remain unresolved.

Contextual Notes

Participants note that the problem lacks explicit information about the number of moles per trial, which may affect the calculations. There is also uncertainty regarding the interpretation of the total volume in relation to the trials.

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Homework Statement


Calculate the initial molarity of S2O32- in each trial given that each trial has 1.00 mL of .010 M Na2S2O3 and a total volume of 7.00 mL.


Homework Equations


mol = g/(g/mol)
M1V1=M2V2

The Attempt at a Solution


(1)(.01)=7x
.0014=x
 
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Keep trying.
 


Hmm. Well that's really not that helpful to me. Do you have a hint on what I should do? I mean, I wouldn't be asking on this forum if I wasn't in need of help.
 


Can anyone help me out with this? I'm stuck.
 


Easier to use the definition of molarity. How many moles compound in each trial? How much volume of finished solution in each trial? Calculate the ratio.
 


symbolipoint said:
How many moles compound in each trial? How much volume of finished solution in each trial? Calculate the ratio.

It does not give the number of moles per trial. The question written above is all the information given.

The total volume is 7.00 mL. Is that how much volume of finished solution would be in each trial?
 


The total volume is 7.00 mL. Is that how much volume of finished solution would be in each trial?

Yes.
 


I'm still struggling.
I've calculated the grams of Na2S2O3 = 1.58 g, but I'm still confused as to how I get the molarity of S2O3
 


TypeFun said:
I'm still struggling.
I've calculated the grams of Na2S2O3 = 1.58 g, but I'm still confused as to how I get the molarity of S2O3

You have the molarity of the stock solution. You have the volume of a trial. These are enough to calculate molarity of a trial.
 

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