Transcript http://www.sinc.sunysb.edu/Class/orgolab/vacfilt/vacfilt~.ppt

VACUUM FILTRATION
Yuson will
show you
how to do a
vacuum
filtration.
Scroll down.
VACUUM FILTRATION STEP #1
Clamp a filter
flask so that it
rests on the
base of a ring
stand.
VACUUM FILTRATION STEP #2
Buchner
funnel
Select and
insert a
piece of filter
paper that
just fits the
bed of the
Buchner
funnel.
VACUUM FILTRATION STEP #3
Place a Filtervac
adapter on top
of the flask, and
set the Buchner
funnel into the
adapter.
Attach a thickwalled hose to
the side arm of
the flask.
Connect this
hose to a trap,
as shown in the
next step.
VACUUM FILTRATION STEP #4
to the
filter
flask
Assemble a
trap, whose
purpose is to
catch water
that might back
up if there is a
change in
pressure.
Connect the
trap to the filter
flask.
Do not turn the
water on yet.
THE TRAP IN USE DURING FILTRATION
In steps #5-6,
there will be a
vacuum when
you turn on
the aspirator
faucet and
close the
system with a
pinch clamp.
VACUUM FILTRATION STEP #5
(If your solvent is non-volatile,
you may use it to pre-wet the
filter paper.) Pour the first portion
of filtration mixture into the funnel
-- take care that the paper
doesn’t float up!
Turn on the water and close the
outlet hose with the pinch clamp
to start the vacuum. Proceed
immediately to step #6.
VACUUM FILTRATION STEP #6
If you don’t have a
vacuum, grasp the
sides of the funnel
and hold it down.
This should make a
seal.
Once there is a
vacuum, the liquid
will flow through
quickly.
VACUUM FILTRATION
Buchner funnel
with filter paper
trap connected to the aspirator
(shown in the closed position)
Filtervac
thick-walled hose
filter flask clamped resting on the
base of the ring stand
VACUUM FILTRATION STEP #7
Continue if necessary to filter the rest of the mixture in fairly large portions.
At the end of the filtration, the liquid will have been sucked through and the
solid will appear quite dry (it actually won’t be completely dry yet).
You should open the pinch clamp before you turn off the faucet. Otherwise,
the vacuum may suck the water back into the trap.