Help with mass and molar concentrations

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SUMMARY

The discussion focuses on calculating the mass and molar concentrations of gases in air at 37 °C and 1.0 atm pressure, specifically for O2, CO2, and N2. The molecular weights provided are 0.032 kg/L for O2, 0.028 kg/L for N2, and 0.044 kg/L for CO2. To solve the problem, it is essential to assume a volume of 1L, as the percentages given represent mole fractions rather than mass or volume percentages. Utilizing the ideal gas law (PV=nRT) is unnecessary since the volume will cancel out in the final calculations.

PREREQUISITES
  • Understanding of the ideal gas law (PV=nRT)
  • Knowledge of molecular weights of gases
  • Familiarity with concentration calculations
  • Basic principles of gas mixtures and mole fractions
NEXT STEPS
  • Calculate mass concentrations of O2, CO2, and N2 using the given molecular weights.
  • Explore Avogadro's law and its implications for gas volumes and moles.
  • Learn about the relationship between mole fractions and partial pressures in gas mixtures.
  • Investigate the concept of concentration in different contexts, including mass and molar concentrations.
USEFUL FOR

This discussion is beneficial for chemistry students, educators, and anyone involved in gas law applications or concentration calculations in scientific contexts.

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Homework Statement


At 37 ° C and 1.0 atm of pressure, air is 21.2% O2, 0.15 % CO2 and 78.65 % N2. Determine the mass and molar concentrations of each of the gases in the air.


Homework Equations


Molecular weight of O2=.032kg/L
Molecular weight of N2=.028kg/L
Molecular weight of CO2 = .044kg/L
PV=nRT

The Attempt at a Solution


I don't know how to start because I am not given V, mass, or number of moles (so the ideal gas law isn't useful). I am also not sure if the percentages given are in terms of mass/volume/number of moles so I am very confused. How should I approach this problem?
 
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Assume V = 1L. Alternatively derive formula for concentration using V as a variable - in the end it will miraculously cancel out. These are not mass percentages (think what Avogadro's law tells you about volume/moles).
 

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