netnofeels
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What does this mean?
Im following some instructions and I really dont understand what this means. It says 'the residue was vacuum distilled, and the fraction boiling at
75-85°C/8mmHg weighed 90g'
The two compounds that should be in there have boiling points of around 200c and and I know its under vacuum but 8mmHg would do nothing. Im thinking
that could be vapour pressure but im not sure and if it was i dont know why that would even matter. What does the 8mmHg mean and how would you be able
to calculate the boiling point it should have under vacuum?
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horribilis
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Quote: Originally posted by netnofeels  | Im following some instructions and I really dont understand what this means. It says 'the residue was vacuum distilled, and the fraction boiling at
75-85°C/8mmHg weighed 90g'
The two compounds that should be in there have boiling points of around 200c and and I know its under vacuum but 8mmHg would do nothing. Im
thinking that could be vapour pressure but im not sure and if it was i dont know why that would even matter. What does the 8mmHg mean and how would
you be able to calculate the boiling point it should have under vacuum? |
Why would the fact that it's under vacuum at 8 mm Hg do nothing? Plug it into a nomograph: https://www.sigmaaldrich.com/chemistry/solvents/learning-cen... A substance with a 200 C atmospheric boiling point should be ~ 72 C boiling point
at 8 mm Hg vacuum. The units mm Hg are units for pressure.
[Edited on 1-6-2019 by horribilis]
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wg48temp9
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Yes units of absolute pressure. I guess the OP was thinking 8mm below atmospheric pressure
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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