Rate of effusion dependance on pressure

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SUMMARY

The rate of effusion of gas is directly proportional to the mean speed of gas molecules, which is defined by the root mean square (RMS) speed equation, RMS speed = √(3RT/M). While the rate of effusion is inversely proportional to the square root of molar mass, it is also influenced by pressure. By utilizing the statistical mechanical equation of state, P = nkT, it becomes clear that an increase in pressure leads to a higher number density of molecules, thereby increasing the rate of effusion through an opening.

PREREQUISITES
  • Understanding of the ideal gas law (PV = nRT)
  • Familiarity with root mean square (RMS) speed calculation
  • Knowledge of molar mass and its impact on gas behavior
  • Basic concepts of statistical mechanics, particularly the equation of state (P = nkT)
NEXT STEPS
  • Study the relationship between pressure and molecular density in gases
  • Explore the derivation and implications of the root mean square speed equation
  • Investigate the effects of temperature on gas effusion rates
  • Learn about the kinetic molecular theory and its applications in gas behavior
USEFUL FOR

Chemistry students, physicists, and anyone interested in understanding gas dynamics and the principles governing effusion rates.

jd12345
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In my class rate of effusion was told to be directly proportional to the mean speed of gas molecules which is intuitive and i understand. RMS speed of molecules is √3RT/M
So rate of effusion is inversely proportional to sqaure root of molar mass

But i don't understand how rate of effusion is directly proportional to pressure
RT = PV
So RMS speed = √PV/M so rate of effusion should be proportional to square root of pressure right? But apparently its not, please explain me why

Thank you!
 
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jd12345 said:
In my class rate of effusion was told to be directly proportional to the mean speed of gas molecules which is intuitive and i understand. RMS speed of molecules is √3RT/M
So rate of effusion is inversely proportional to sqaure root of molar mass

But i don't understand how rate of effusion is directly proportional to pressure
RT = PV
So RMS speed = √PV/M so rate of effusion should be proportional to square root of pressure right? But apparently its not, please explain me why

Thank you!

It makes more sense if you replace PV=RT with the statistical mechanical equation of state,
P = nkT. Then the number density (number of molecules per unit volume) is directly proportional to the pressure. The more molecules per unit volume, the greater the effusion through an opening.
 

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