Solve Titration Mass Problem: Unweighed Sample, 5% Acetic Acid

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Discussion Overview

The discussion revolves around a titration problem involving acetic acid in vinegar, specifically investigating the manufacturer's claim that the vinegar is 5% acetic acid by weight. Participants explore how to relate molarity and density to determine the weight percentage without direct weighing of the sample.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant states the molarity of acetic acid is 0.23M in a 10.0 mL solution and questions how to relate this to the weight percentage without weighing the sample.
  • Another participant suggests calculating how much acetic acid would be present in 1 liter if it were 5% by weight, prompting a discussion about the relationship between weight and molarity.
  • A participant calculates that 0.23M corresponds to 13.81 g/L of acetic acid, asserting this should align with the manufacturer's claim of 5% weight.
  • Some participants express confusion about the calculations and the implications of the density provided, with one noting that the density of 1.0 g/mL should allow for mass calculations.
  • One participant presents a calculation showing that 0.24M results in 1.4% by weight, while 0.83M would correspond to 5% by weight, questioning the accuracy of the manufacturer's claim.
  • Another participant reinforces that the density of 1.0 g/mL was explicitly given and should be used to calculate the mass of the solution.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of the calculations and the implications of the density provided. There is no consensus on whether the manufacturer's claim is accurate, as some participants suggest potential errors in calculations while others defend their reasoning.

Contextual Notes

Participants note the absence of direct weighing and the reliance on molarity and density for calculations. There are unresolved aspects regarding the assumptions made about the density and its application in the calculations.

Whalstib
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Homework Statement


Hi,
A titration revealed I have .23M acetic acid (HC2H3O2) in a 10.0mL soln.

I was not asked the weigh the sample at any time but our question is:
"The manufacturer of this vinegar claims it is 5% by weight. Ue your results and a density of 1.0g/mL to investigate this claim"

I'm at a loss to determine any results based weight with no weighing involved...I thought the molarity answered any questions about concentration.





Homework Equations


Acetic acid 60.05g/mol
H2O 18.02g/mole
No samples weighed at any time

titration began with 10.0mL vinegar and 10.0mL H2O



The Attempt at a Solution


My only guess is acetic acid is 60.05 g/mol at .23M gives me 13.81 grams times .05 gives me .69 g/mL which would be 5% of the molecular weight...?

I'm I getting close?

Thanks as always!

Warren
 
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If you have 5% by weight, how much do you have in 1 litre? Which is how many moles?
 
See that's confusing because I know the molarity is .23M. So I have .23 moles/liter which is 13.81 g/L acetic acid. That's a fact. This should relate exactly to 5% in manufacturers claim is accurate...
 
Perhaps that's the point - sometimes claims can be misleading. Or perhaps you made a mistake in your calculation. If there was more acid than claimed I'd look at the ingredients to see if there was any other source but as it's less..?
 
Whalstib said:
"The manufacturer of this vinegar claims it is 5% by weight. Ue your results and a density of 1.0g/mL to investigate this claim"

I'm at a loss to determine any results based weight with no weighing involved...

You are given volume (10 mL), you are given density... Can't you simply calculate mass of the sample?

--
methods
 
We're not given the density just molarity. All I can figure since it's vinegar they have told us the soln is HC2H3O2 + H2O with 100% H2O being 1.0g g/mL.

Here's my final answer:
.24M= (.24 moles/L HC2H3O2)(60.05 g/mole)= 14.41g/L= .014g/mL = 1.4% by weight...

For 5% the eqn would be:
.83M= (.83moles/L)(60.05g/mole)=50.0g/L= .05g/mL= 5% by weight...right?

Thanks,

Warren
 
Whalstib said:
We're not given the density just molarity.

Whalstib said:
Ue your results and a density of 1.0g/mL to investigate this claim"

You were specificially told to use 1.0 g/mL density, aren't you?

Here's my final answer:
.24M= (.24 moles/L HC2H3O2)(60.05 g/mole)= 14.41g/L= .014g/mL = 1.4% by weight...

For 5% the eqn would be:
.83M= (.83moles/L)(60.05g/mole)=50.0g/L= .05g/mL= 5% by weight...right?

And you did exactly what you were expected to do - you used density to calculate mass of the solution (assuming 1 mL is 1 g is exactly the same), yet you claim you don' know how

--
 
actually...you have done it...:biggrin:
 

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