How to Convert a Number Concentration into Volume Mixing Ratio?

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Discussion Overview

The discussion focuses on converting a number concentration of molecules into a volume mixing ratio under varying pressure and temperature conditions. It involves theoretical and practical aspects related to the Ideal Gas Law and atmospheric science definitions.

Discussion Character

  • Homework-related
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant presents a homework problem involving the conversion of a number concentration of 15 x 10^12 molecule/cm3 into volume mixing ratios at specified conditions.
  • Another participant questions the definition of volume mixing ratio, expressing frustration with how atmospheric sciences define terms, suggesting a need for clarity on the definition to proceed.
  • A participant expresses uncertainty about how to approach the problem, indicating that knowing the required units would help in understanding the solution process.
  • Another reply suggests that the participant should look up the definition of volume mixing ratio in their notes or online as a starting point for solving the problem.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the definition of volume mixing ratio, and there is uncertainty regarding the approach to the homework problem. Multiple competing views on how to define and apply the concept remain unresolved.

Contextual Notes

Limitations include the lack of clarity on the definition of volume mixing ratio and the specific units required for the solution, which may affect the ability to proceed with the calculations.

Geo_Zegarra2018
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Homework Statement


Convert a number concentration of 15 X 10^12 molecule/cm3 into volume mixing ratio at:

a) 1 atm pressure, and 20 C temperature.

b) 500 mbar pressure, and 253 K temperature.

Using the Ideal Gas Law, calculate:

a) Loshmidt’s number (# of molecules/cm3 of air, at standard atmospheric conditions “STP”, 1 atm pressure, and 273 K)

b) Density of atmosphere at “STP”

Homework Equations

The Attempt at a Solution

[/B]
I converted 15 x 10^12 molecule/cm^3 to mol/cm^3
 
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How is the volume mixing ratio defined (I hate the way gases are treated in the atmosphere sciences, they define everything their own way just as if to make things incomprehensible to physicists and chemists :wink: )? What information do you need to directly apply this definition?
 
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I honestly don’t know. Like if it told me what units to solve for I would probably have a better idea how to proceed this problem
 
Then you have to google for the definition or find it in your notes. That's your starting point.
 

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