Gas impingement flux, problem in substituting constants

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SUMMARY

The discussion focuses on deriving the gas impingement flux density equation, specifically ∅=3.513*10²²P/√(MT), where P is pressure in torr and M is the molar mass of the molecule. Participants highlight the necessity of including a factor of π in the square root of the original equation ∅=P/√(2mkT) to achieve the correct constant. The conversation emphasizes the importance of unit consistency, particularly in converting pressure scales and understanding the SI units for mass and molar mass.

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  • Familiarity with SI units and conversions
  • Knowledge of Avogadro's number and its application
  • Basic principles of thermodynamics and kinetic theory
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jjshan
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Homework Statement


gas impingement flux density is given by ∅=P/[itex]\sqrt{}2mkT[/itex]
where m- mass of a molecule

show that
∅=3.513*1022P/[itex]\sqrt{}MT[/itex]
where pressure in torr and M-molar mass of molecule
then ∅ in molecules per cm2 per second

Homework Equations




∅=3.513*1022P/[itex]\sqrt{}MT[/itex]
where pressure in torr and M-molar mass of molecule
then ∅ in molecules per cm2 per second

The Attempt at a Solution



i substitute 1/133 to change pressure scale to torr and multiply by square root of Avogadro no and divide it by square root of 2∏k but i couldn't get appropriate constant. how derive the equation in given scale?
 
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jjshan said:
Homework Statement
gas impingement flux density is given by ∅=P/[itex]\sqrt{}2mkT[/itex]
where m- mass of a molecule

It looks like you left out a factor of ##\pi## in the square root of the equation.

Consider:

What are the units of ∅ in the SI system?

What are the units of m in SI system?

What are the units of M?
 

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