Vacuum Filtration Equipment Assembly
Attach the rubber hose to the aspirator.
The aspirator is a device that produces suction when the water is turned on. Be sure the aspirator is working first by turning on the water and putting your finger over the suction port. If you don't feel suction, ask your lab instructor for help or use a different aspirator.
Make the connection by pushing the rubber hose over the port on the side of the aspirator. Be sure you are attaching the rubber hose that comes from the water bottle's short piece of glass tubing. Failure to do observe this may make it possible for foreign substances to enter the water supply.
Using
a vacuum adapter, position
either the Hirsch or Buchner
funnel on top of the filter flask.
The vacuum adapters seal the top of the filter flask to the bottom of the funnel. Without the vacuum adapter, air leaks develop that will slow down the filtration process.
Place filter paper in the funnel.
Circular filter paper
comes in many different
sizes; be sure you choose a size that covers all the holes but still fits easily
within the filter funnel.
Wet
the filter paper with a small
amount of cold recrystallization solvent.
It is necessary to wet the filter paper to secure it to the bottom of the filter funnel. Without this step, the filter paper may float when the solid/solvent mixture is poured. Consequently, solid product is lost as it passes around the filter paper ending up in the filter flask below. When wetting the filter paper do not assume that water is an appropriate solvent. Use the same solvent that suspends your solid product.