Acetone Vapor pressure vs boiling point 1

[saleda]

The following data is of Acetone Boiling Point at different pessures.
-59.4 1 torr
-40.5 5 torr
-31.1 10 torr
-9.4 40 torr
-2 60 torr
7.7 100 torr
22.7 200 torr
39.5 400 torr
46 500 torr
51 600 torr
55 700 torr

At my location ATM pressure is 727 mmHg. when I apply vacuum and gauge display 680 mmHg that would mean 47 mmHHg pressure remains. Acetone should boil between -9.4 to -2 oC. whereas it does not do so.
To boil acetone at 680 mmHg we keep Temp between 50-55 oC.
Are we supplyng more heat than required?
Am I missing something.
Even If we take Latent heat(29.48 Kj/mol at 680 mmHg) in consideration , Can't we vaporize acetone at room temperature(25-30 oC)?

Thanks
Saleda.

 

[ione]

Those you've reported are absolute vapour pressure values. At 25 °C temperature the absolute vapour pressure of acetone is 229.5 mmHg (absolute)

 

[StoneCold]

Ione is right.
The value of 680 mm Hg shown on the gauge is absolute pressure, that is why it matches up with the boiling point data points you typed in.
There is no correction factor to be added or subtracted here.

Regards
StoneCold

 

[saleda]

then what should be the reading at pressure gauge to boil the acetone at 40 oC ?

 

[Latexman]

A little over 400 mm Hg.

Good luck,
Latexman

 

[saleda]

Dear Latexman
Now that is what confusing me....
If you have refered to the data I have typed above then as the reading in Gauge decreses with that boiling point decreases, then why should I install heavy Vacuum Pump and achieve maximum vacuum achiievable.
At 680 mmHg boiling is at 50-55 oC
At 400 mmHg boiling is at 40-42 oC ? ?

Please clearify...

Thanks
Saleda

 

[Latexman]

It's clear to me. I think you are confused on absolute and guage pressures. It may be caused by the word guage in pressure guage. A pressure guage can measure either absolute pressure or guage pressure. It depends on which type is bought. The pressure guage you are reading measures absolte pressure in mm Hg. As SC said, it measured 680 mm Hg absolute pressure. If it measured guage pressure, it would say -47 mm Hg if it was calibrated to zero at 727 mm Hg absolute pressure being "atmospheric pressure". And, you'd have 47 mm Hg of vacuum. Do you have a copy of Felder and Rosseau's "Elementay Principles of Chemical Processes" or something like that. You need to brush up on Pressure.

Good luck,
Latexman

 

[25362]

The Antoine equation in Perry's VIII ed.:

log Psat = A - B/(T+C)

P in torr, T in oC
A=7.11714
B =1210.595
C = 229.664

Range of applicability: from -13 to +55oC.