The photo below shows the three types of filtering funnels used in the organic chemistry labs. From left to right: Buchner funnel and the grey rubber adaptor for it, stemmed funnel, and stemless funnel.
Buchner: say "byoock ner"
The Buchner funnel is the white porcelein funnel in your lab drawer. You need a grey or black adaptor or a stopper with a hole in it to connect it to a side arm flask. The Buchner is used exclusively for vacuum filtrations. The adaptor forms a snug seal so that when reduced pressure is applied to the vacuum flask, liquid poured into the Buchner is sucked into the flask quickly.
If you are missing an adaptor or yours does not fit, you can come to the stockroom and find one that fits in the bin on the cart by the door.
Stemmed funnel
Stemmed funnels are used for gravity filtration. They are also used for miscellaneous tasks such as filling round bottom flasks with liquids.
Stemless funnel
Stemless funnels are designed for "hot filtrations". This procedure is used to filter a hot solution of a compound in a recrystallization process; the "no-stem" feature prevents the compound from crystallizing out too soon, e.g., in the stem of the funnel.
In practice, stemless funnels can also be used in any gravity filtration.
Location: the Buchner and stemmed funnels are student lab drawer equipment. Stemmed funnels will be placed in the labs as community glasswhere when needed.
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