Chemistry How to Convert a Number Concentration into Volume Mixing Ratio?

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SUMMARY

The discussion focuses on converting a number concentration of 15 x 1012 molecule/cm3 into a volume mixing ratio under specified conditions using the Ideal Gas Law. Participants explore calculations for Loshmidt’s number and atmospheric density at standard temperature and pressure (STP). The conversation highlights the need for clarity in definitions related to volume mixing ratios, particularly in atmospheric sciences, which can be confusing for those with a background in physics and chemistry.

PREREQUISITES
  • Understanding of the Ideal Gas Law
  • Knowledge of Loshmidt’s number and its significance
  • Familiarity with standard temperature and pressure (STP) conditions
  • Basic concepts of volume mixing ratios in atmospheric sciences
NEXT STEPS
  • Research the Ideal Gas Law and its applications in atmospheric chemistry
  • Study the calculation methods for Loshmidt’s number
  • Explore definitions and calculations related to volume mixing ratios
  • Investigate the relationship between pressure, temperature, and gas density
USEFUL FOR

Students in atmospheric sciences, chemists, physicists, and anyone involved in gas concentration calculations and atmospheric modeling.

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

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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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