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#1




vapor density from liquid density
I have a question... is it possible to obtain vapor density of a given organic compound (say acetone) from its liquid density? if so please explain the procedure or if there are any tables available, please direct me to the same. thanks in advance guys.

#2




Re: vapor density from liquid density
It is not possible and the vapor density will be a MUCH stronger function of temperature than the liquid density is. The CRC Handbook of Chemistry and Physics has a few tables. I am sure there must be better references but I don't know what they are.

#3




Re: vapor density from liquid density
thanks for the answer.... i already checked the crc handbook and all data are given for liquids and not gases...
in the MSDS relative densities are given, like if air has density of 1 then acetone has 3.... my question is can we directly multiply the density of air at a given temperature by this number to get the density of acetone or whatever gas? 
#4




Re: vapor density from liquid density
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#5




Re: vapor density from liquid density
thanks again... so if the density of air at 28 C is 1.166 kg?m3, it can be multiplied by 3 so long as acetone is at the same temperature, right?

#6




Re: vapor density from liquid density
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Edit: This page gives saturated vapor pressure vs temperature. I note it also gives Van Der Waals constants. I would ignore the specific gravity and figure density directly from the Ideal Gas Equation (using molecular weight, temperature, and vapor pressure) or for better accuracy, Van Der Waal's equation (and the given constants). (Van Der Waal's equation has two real gas corrections vs Ideal Gas Law) Last edited by JohnS; 12282010 at 06:24 AM. 
#7




Re: vapor density from liquid density
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i am not able to see the link for the page (saturated vapor pressure vs temperature... can you upload it again? can i use the ideal gas equation itself? cause i cant calculate the container volume as its shape is a bit complex... what will be the error percentage approximately? and can i use the equations for vapor pressure given in wikipedia for the respective gases? are they the equations for saturated vapor pressures? i think i have to apply saturated vapor pressures because all the vapors are produced through bubbling air into the respective liquids... so the vapors must be saturated i think. Last edited by prakash; 12292010 at 01:05 AM. 
#8




Re: vapor density from liquid density
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http://en.wikipedia.org/wiki/Acetone_(data_page) Yes, ideal gas, PV = nRT From mass and molecular weight n = m/Mw substituing, m/V = P*Mw/(R*T), m/V is density Your "vapor" will be a combination of air and acetone vapor. The ambient air pressure will be reduced by the vapor pressure of the acetone. You may use Dalton's Law of Partial Pressure to independently calculate the air density and acetone density, and add them for the mixture. Last edited by JohnS; 12292010 at 02:27 AM. 
#9




Re: vapor density from liquid density
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thanks so much.... what i have to do is determine the ppm content of a volatile gas in air... so i have divided two quantities, each of which is a ratio of the product of mass flow rate and density to the molar mass. so dividing the two quantities (gas and air respectively), i get the ppm after multiplying by a million. i know the temperature of the mixture of air and gas at the exit, so i got the density of air from standard tables at that temperature, and now since i got the density of the gas too from the ideal gas law, i can proceed further.. i only hope i got the formulas right? can u just check it up and tell me? 
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