What Is the Correct Theoretical Yield of HNO3 in This Chemistry Problem?

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Discussion Overview

The discussion revolves around a chemistry homework problem concerning the theoretical yield of nitric acid (HNO3) from a reaction involving nitrogen dioxide (NO2) and water (H2O). Participants analyze the stoichiometry of the reaction and the calculations performed by the original poster to identify any mistakes and clarify the theoretical yield.

Discussion Character

  • Homework-related, Technical explanation, Debate/contested

Main Points Raised

  • The original poster calculates the limiting reagent as NO2 and finds a theoretical yield of HNO3 based on their calculations.
  • Some participants question the stoichiometry of the reaction, specifically the number of moles of H2O required, suggesting a possible error in the original poster's understanding.
  • There is a mention of a mistake pointed out by a participant, but it is noted that this mistake does not affect the final answer.
  • Another participant raises a concern about a potential typo in the book, indicating that the book's answer may refer to grams of NO2 instead of HNO3, which could lead to confusion.

Areas of Agreement / Disagreement

Participants express differing views on the stoichiometry of the reaction and the calculations, with some agreeing on the correctness of the conclusion while others point out potential errors. The discussion remains unresolved regarding the exact nature of the mistake and the correct answer provided in the book.

Contextual Notes

There are unresolved questions about the accuracy of the book's answer and the implications of the stoichiometric calculations. The discussion highlights the dependence on precise definitions and the potential for typographical errors in educational materials.

ducmod
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Homework Statement


Hello!
I would be grateful for your help on finding my mistake - somehow my answers are
wrong compared to the answer from the book.
Here is the exercise from a paragraph on gases (cumulative gas law, basics):

Consider the reaction for the synthesis of nitric acid:
3NO2 + H2O = 2HNO3 + NO
(a) If 12.8 L of NO2 measured at STP, is allowed
to react with 14.9 g of water, find the limiting
reagent and the theoretical yield of HNO3 in
grams.

Here is my solution:

1 mole of gas at STP = 22.4 L; 12.8 L gives 0.5714 moles of NO2
1 mole of H2O = 18.016 g; 14.9 g = 0.827 moles of H2O

The limiting reagent is NO2, because
3 moles NO2 + 2 moles of H2O
0.5714 moles NO2 requires only 0.381 moles of H2O, but we have 0.827 moles of H2O

1 mole of NO2 = 46.007 g
0.5714 moles of NO2 = 26.288 g
Theoretical yield of HNO3:
3 moles of NO2 = 2 moles of HNO3
0.5714 moles of NO2 = 0.3809 moles of HNO3

1 mole of HNO3 = 63.008
0.3809 moles of HNO3 = 24.001 g

Thank you!
 
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ducmod said:
3 moles NO2 + 2 moles of H2O
Why 2 moles of H2O?
The conclusion is still right.

Looks right.
I don't think you have to work with decimal numbers of molar masses, they are very close to integers for the involved elements.
 
There is the mistake mfb already pointed out, but it doesn't influence the final answer.

What is the answer given in the book?
 
mfb said:
Why 2 moles of H2O?
The conclusion is still right.

Looks right.
I don't think you have to work with decimal numbers of molar masses, they are very close to integers for the involved elements.
Thank you! Sorry, yes, only one mole of H2O.
 
Borek said:
There is the mistake mfb already pointed out, but it doesn't influence the final answer.

What is the answer given in the book?
I think the problem was in the question - there is some typo in the book, because exercise is asking about theoretical yield of HNO3,
while the book gives answer on grams of NO2
 

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