7 replies to this topic

[v8landy]

Hi

My mind has gone blank today!

I need boiling points of Acetone, Pentane, Methanol and Dichloromethan at 5 psi g.

I think I involves Rauolts Law, but maybe I am wrong?

Thanks

[Qalander (Chem)]

Dear James Hello/Good morning,Why should'nt you google with key words 'Boiling Points of Acetone, Pentane, Methanol and Dichloromethane at slightly above atmospheric pressures' just recieved 1870 hits one sample here http://adt.curtin.ed.../03Chapter2.pdf
Hope this helps
Best Regards
Qalander

[v8landy]

Thanks Qalander

But I am trying to calculate the pressures not google them. The link you gave made no reference to what I need.

[gvdlans]

One way of doing this is to use the Antoine equation, that has a form such as:

Log(Pvap) = A-B/(C+T)

Note that at the boiling point Tboil, the vapour pressure is equal to the system pressure (Pvap = P). Therefore:

Log (P) = A-B/(C+Tboil)

So:

Tboil = B/(A-Log(P)) - C

Be aware that you should use correct units for Tboil and P. These units must be consistent with the parameters A, B and C that you use.

Also be aware that the Antoine equation should not be used outside the defined temperature limits Tmin, Tmax

See also http://en.wikipedia....ntoine_equation

Good luck!

[Qalander (Chem)]

Thanks Qalander

But I am trying to calculate the pressures not google them. The link you gave made no reference to what I need.

Sorry Dear, I could'nt be of much help; as I had to leave in a hurry for some other occupancy.

Thanks to 'gvdlans' as his reply might have been helpful, I assume!

Best regards
Qalander

[v8landy]

Thanks to you both, with the above equation and the following web site for A, B and C values I can now calculate at any pressure

http://ddbonline.ddb...culationCGI.exe

[v8landy]

I have also found this web site

http://www.s-ohe.com/Vp_calc.html

It works the other way round! By in-puting a temperature it gives you the pressure in mmhg. So you could guesstimate or use it to cross check the above calculations.

[ankur2061]

I have also found this web site

http://www.s-ohe.com/Vp_calc.html

It works the other way round! By in-puting a temperature it gives you the pressure in mmhg. So you could guesstimate or use it to cross check the above calculations.

Hi,

Our good old cheresources has a lovely spreadsheet titled

"Vapor Pressure from Antoine Coefficients"

Here is the link:

http://www.cheresour.../software.shtml

This will probably solve the problem of all people who are looking for VP data for the most common of all chemicals within the temperature ranges which bound the Antoine constants given in the spreadsheet. You can add components if you desire so to the list in the spreadsheet.

Regards,
Ankur.