Calculating O2 Volume from First-Order Decomposition of Hydrogen Peroxide

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Discussion Overview

The discussion revolves around calculating the volume of oxygen produced from the first-order decomposition of hydrogen peroxide (H2O2) in an aqueous solution. Participants explore the relationship between the decomposition of H2O2 and the resulting volume of O2, considering factors such as time, pressure, and the ideal gas law.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant states the decomposition reaction of hydrogen peroxide produces half a mole of oxygen for every mole of peroxide decomposed.
  • Another participant questions how much peroxide will decompose over the given time period of 12.4 minutes.
  • A participant calculates that 1.23e-24 moles of H2O2 will decompose, leading to a corresponding amount of O2, but expresses uncertainty about finding the volume.
  • One participant suggests using the ideal gas law to find the volume of O2 produced.
  • Another participant recalculates and proposes that 0.577 moles of H2O2 decomposed, resulting in 0.289 moles of O2, but is unsure about the correctness of this calculation.
  • There is a correction regarding whether the calculated amount of H2O2 is the amount decomposed or remaining, indicating a potential misunderstanding in the calculations.

Areas of Agreement / Disagreement

Participants express differing views on the calculations and the correct application of the ideal gas law. There is no consensus on the final volume of oxygen produced or the accuracy of the mole calculations.

Contextual Notes

Participants highlight the need for clarity on the amount of H2O2 decomposed versus remaining, as well as the application of pressure in the ideal gas law, which remains unresolved.

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Homework Statement


Hydrogen peroxide undergoes a first-order decomposition to water and O2 in aqueous solution. The rate constant at 25°C is 7.40e-4s. Calculate the volume of O2 obtained from the decomposition reaction of 1.00 mol H2O2 at 25°C and 740 mmHg after 12.4 min.

Homework Equations


ln[H2O2]= -kt + ln[H2O2]0


The Attempt at a Solution


12.4 minutes = 744s
k = 7.4e-2

I started using the above equation to calculate the concentration of H2O2 and then tried to get O2 from there, but that just gave me molarity and I'm not sure how to find volume. Also, the equation does not include the pressure, so I am not sure if I am using the correct equation, but I can't find anything else in the book.

Thanks :-)
 
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How much oxygen produced per mole of peroxide decomposed? Look at the reaction equation.

Pressure is needed only for ideal gas equation here.
 
1/2 mole of oxygen is produced her mole of peroxide decomposed, but I'm not sure I understand how that helps me.
 
How much peroxide will be decomposed during 12.4 minutes?
 
I think 1.23e-24 moles of H2O2 will decompose, which means 6.14e-25 moles of O2 will be produced, but I still need to find volume. Can I use the ideal gas law to find this?
 
You are on the right track now whe it comes to the approach to find the volume, but your numbers (in the range of 10-24 moles) are for sure wrong.
 
wow. i just recalculate that and have no idea how i got that number.
does .577 moles of H2O2 decomposing sound more reasonable? and then .289 O2 formed?

using ideal gas law, PV=nRT I have (740)V=.289(62.36)(298.15). V=7.26, but that is not the right answer...
im lost.
 
Looks to me like you are in the correct range with these numbers.

Check whether 0.577 is decomposed - or left, that's most likely mistake. I am leaving for an hour or so now, so you are on your own.
 
Oops. That was the amount left, not decomposed.

Thanks so much for your help! I really appreciate it!
 

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