Neutralization Reaction: Volume of NaOH(aq) Needed to Neutralize H3PO4(aq)

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Discussion Overview

The discussion revolves around calculating the volume of 0.350 mol/L NaOH(aq) required to neutralize 54.5 mL of 1.31 mol/L H3PO4(aq). Participants explore the stoichiometry of the neutralization reaction and the appropriate equations to use in this context.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant states the need to use the equation c1v1 = c2v2 but expresses difficulty in obtaining the correct answer.
  • Another participant suggests writing the reaction equation to clarify the stoichiometry involved.
  • There is a contention regarding the correct stoichiometric ratio of NaOH to H3PO4, with some asserting it is 3:1.
  • Several participants indicate that earlier equations presented are incorrect, specifically noting that the relationships between concentrations and volumes may have been reversed.
  • A participant proposes a modified equation, suggesting that if the moles of H3PO4 are multiplied by 3, a 1:1 ratio with NaOH can be established.
  • Ambiguity in the notation used by participants leads to confusion about which species is represented in the equations.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct approach to the problem, with multiple competing views on the stoichiometry and the appropriate equations to use remaining unresolved.

Contextual Notes

There is uncertainty regarding the correct stoichiometric relationships and how to apply them in the context of the neutralization reaction. Some assumptions about the reaction ratios and the application of equations are not clearly defined.

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Homework Statement



what volume of 0.350 mol/L NaOH(aq) is required to completely neutralize 54.5 mL of 1.31 mol/L H3PO4(aq)?

Homework Equations



c1v1 = c2v2

The Attempt at a Solution



You would just solve for v2 but I am not getting the right answer for some reason.
 
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Yes, the equation is wrong.

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Elaborate.
 
No, you follow my earlier advice - write reaction equation & read the page linked to.
 
so, 3c1v1 = c2v2

then v1 = c2v2/3c1 ?

This would give me 6.80x10^-2 L.
 
You got it reversed.

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  • #10
68 mL is not a correct volume of NaOH.
 
  • #11
Borek said:
68 mL is not a correct volume of NaOH.

Yes, I learned the hard way.

I wrote the balanced equation of H3PO4 + 3 NaOH -> 3 H2O + Na3PO4

3CnaohVnaoh = Ch3po4Vh3po4

Is this wrong?
 
  • #12
Yes, this is wrong. You got it reversed.

How many moles of NaOH needed to react with one mole of H3PO4? What shoudl be multiplied by three - number fo moles of NaOH, or number of moles of H3PO4?

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  • #13
Borek said:
Yes, this is wrong. You got it reversed.

How many moles of NaOH needed to react with one mole of H3PO4? What shoudl be multiplied by three - number fo moles of NaOH, or number of moles of H3PO4?

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The H3PO4. This way you would have a 1:1 ration, correct?
 
  • #14
Hard to say what you mean.

Ratio of 1:1 - what to what?
 
  • #15
If you multiply the H3PO4 by 3, you would have a ratio of 1:1 with NaOH:H3PO4.

So you could write c1v1=3c2v2?
 
  • #16
If 1 is NaOH and 2 is H3PO4 then yes. But you should be more specific, as what you have wrote is ambiguous.

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