Dear researchers,
Can you teach me how much total pressure is exerted inside a 50 ml sealed Teflon vessel at 250 degree C containing 20 ml water, 5 ml ethanol and 5 ml Toluene?
Given that at 250 degree Celsius,
vapor pressure of water is ~ 4 mPa
vapor pressure of ethanol is ~ 6 mPa
Pavapor pressure of Toulene is ~ 2 mPa
Does Dalton partial pressure apply here? I need the total pressure inside the closed vessel at given temperature for safety.
Best regards,
Hom
Hom,
Dalton's law is adequate in this case, yes.
But I am surprised at the figures that you have for the partial pressures.
At 250 deg C the partial pressure of water will be well above 1bar - surely.
(look at a boiling kettle)
How did you obtain these partial pressures?
They seem far too low, by a factor of a billion or so. A worryingly large factor.
The Vapor pressure of water at 250 C is about 4 Mega Pascals (capital M) not mili pascals. I just did a quick flash by iterating on total pressure until the sum of the vapor fractions added up to 1 with K= y/x = VP/P assuming your vapor pressures in MP were accurate and got P = 4.185 MPA
Hom, to actually answer your question follow these steps:
Guess a pressure (I guessed 4)
Calculate K for each component = VP/P (this equal Y/X)
Vap mole rater = K/(1+K)*total feed rate for each component
total Vap mole rates.
Add up the partial pressures to get a new guess at total pressure
Itertate until sum of partial pressures to get new guess at total pressure
recalculate K = (Vp/P) fr eack component and iterate until total pressure converges (about 3 or 4 iterations is all it takes)
Thank you Rick for your nice suggestion.
Dear James, Its mega pascal (MPa). Sorry for ambiguous symbol.
I will try.
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