mole fraction in the gas phase of a mixture 2

[fish1957]

A closed wood preserving retort contains 200 gallons of coal-tar creosote and 2000 gallons of water. Creosote is a mixture of hydrocarbons distilled from coal tar. It is insoluble in water, has a specific gravity of 1.1, the molecular weight can be assumed to be 162. The A and B coefficients for Antoine's equation:
log VP, mm Hg =[(-.05223*A)/T]+ B
are A = 33649 and B = 5.7296 (T is Kelvin).
The retort is closed and some of the air is evacuated. The temperature of the liquid mix is raised until the temperature of the air/vapor mix in the retort is 245°F. The resulting pressure is 35 psig.
I need to estimate the amount of creosote emitted when this retort is vented to the atmosphere.
May I calculate the mole fraction in the gas phase above this mixture as if the mixture was an ideal solution without significant error? If not, how should it be done?
TIA for your help.

 

[TD2K]

At those conditions and the MW (average) for the creosote, assuming ideal gas behavior would be appropriate IMO.

 

[25362]

To my grasping one has to consider the following factors that may complicate the picture:

1. Creosote is not totally insoluble in water, it may contain 2-4 mass % water. Thus, its VP may be influenced by the Raoult's Law effect. Besides, the mutual water-creosote solubility at higher temperatures is not known.

2. Phenols and naphthalenes may (at least phenol and naphthalene do) form heterogeneous azeotropes with water. There are also homogeneous azeotropes among phenols and xylenes.

3. As the creosote phase is covered by water, one could ask whether the very low VP -as per the quoted Antoine equation- wouldn't be cancelled by the static pressure of the water layer (water head not given) that could interfere with vaporization of creosote.

4. Since it is a mixture of hydrocarbons (phenols, cresols, naphthalenes, etc., composition is not given), on estimating the mass fraction of creosote components in the vapor, one could ask whether the MW of the hydrocarbon vapors is equal to the quoted average MW or a bit lower.

5. For the quoted pressure it appears that either the creosote layer is warmer (temperature not given) than the vapor-air mix, or the pressure -as measured- is generated by heated air and water + the azeotropes (BP lower than 100^oC) mentioned above.