Calculating Partial Pressure of Gases in Tank - Dalton's Law

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Discussion Overview

The discussion revolves around calculating the partial pressures of gases in a tank using Dalton's Law, specifically focusing on a homework problem involving a gas mixture with given mass percentages of CO2, NO, SO2, and H2O. The scope includes mathematical reasoning and problem-solving techniques related to gas laws.

Discussion Character

  • Homework-related, Mathematical reasoning, Debate/contested

Main Points Raised

  • One participant states the need to multiply the percentage of each gas by the total pressure to find the partial pressures but expresses difficulty in arriving at the correct answer.
  • Another participant suggests assuming a total mass of 100g for the sample to simplify calculations, proposing to calculate the moles of each gas based on their masses.
  • This same participant reiterates the method of using mole fractions to relate partial pressures to total pressure, but expresses frustration that their calculations do not yield the expected result for CO2.
  • A different participant questions the accuracy of the provided percentage values, noting that they sum to 100.9%, which could affect the calculated partial pressures.
  • The original poster defends the accuracy of the percentages as stated in their textbook.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the accuracy of the percentage values or the correctness of the calculations, indicating multiple competing views and unresolved issues in the discussion.

Contextual Notes

There are limitations regarding the assumptions made about the total mass and the accuracy of the percentage values, which may impact the calculations of partial pressures. The discussion also reflects uncertainty in the application of Dalton's Law and mole fraction calculations.

Who May Find This Useful

Students studying gas laws, particularly those working on homework related to Dalton's Law and partial pressures in gas mixtures.

yaho8888
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Homework Statement



A sample was collected into a 1.25L tank at 752 mm Hg and analyzed. The analysis showed 92% CO2, 3.6% NO, 1.2% SO2, and 4.1% H2O by mass(key word mass). what is the partial pressure exerted by each gas.




attempt at a solution:
I know that you need to times the percent of gas in the tank by the pressure.
But I try this question so many times keep get me the wrong answer.
so please show step by step solution please.
I am have a quiz tomorrow so please teach me how to do this problem thanks.
 
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This might work: assume 100g total mass sample. Then 92g is CO2, 3.6 g NO etc...

Calculate the mole of each gas with the above masses 92g CO2 = > ? mol CO2

Add up all the moles to get total moles

- mole fraction (mol CO2/total moles)is proportional to partial pressure/total pressure,
- total pressure is given in the problem.
 
eli64 said:
This might work: assume 100g total mass sample. Then 92g is CO2, 3.6 g NO etc...

Calculate the mole of each gas with the above masses 92g CO2 = > ? mol CO2

Add up all the moles to get total moles

- mole fraction (mol CO2/total moles)is proportional to partial pressure/total pressure,
- total pressure is given in the problem.

It dosen;t seem working!
THE ANSWER OF CO2 SHOULD BE 630MM HG
 
are you sure the % values are correct? If you add up all the numbers I get 100.9%, this could make a difference in the partial pressures
 
That's how it is on the book check thousand times!
 

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