Glassware and Equipment
separatory funnel
Separatory funnels are used primarily for extraction procedures, although they are sometimes used to add a solution at a measured rate to a reaction, or to another solution. The sloped walls of the separatory funnel allow easy visibility of different layers in an extraction, and the stopcock at the bottom of the funnel allows the bottom layer to easily be drained out.
The parts of a separatory funnel are the pear-shaped body of the funnel, the straight, narrow stem on the bottom of the funnel, the removable glass stopper which plugs the top of the funnel, the stopcock assembly which regulates the flow of liquid through the stem, and the barrel between the body and the stem, which houses the stopcock assembly.
There are two types of separatory funnels: those with glass stopcocks and those with teflon stopcocks. The operation of both types is the same, but the assembly and care of the two types differ somewhat:
Glass stopcock:
The glass stopcock is actually a ground-glass joint, which will probably require some grease in order to turn smoothly: apply a small amount of grease to the stopcock and insert it through the barrel and turn. If the grease has been evenly applied, the joint should become clear with no striations. Place the small green clip on the opposite end of the stopcock from the handle to hold it in the barrel.
A lot of solvents used in the chemistry labs have a tendency to dissolve the grease, so when you are through using the funnel, store it disassembled and clean.
Teflon stopcock:
The teflon stopcock is a slightly more complicated assembly, but the advantages are that it doesn't freeze or require repeated applications of lubricant grease, and doesn't need to be disassembled to be stored. Do not use grease if you have a teflon stopcock!
Refer to the picture below, and you'll see that this stopcock assembly consists of the teflon stopcock itself, followed by (in order of innermost to outermost part) a white teflon washer, a black rubber "O"-ring, and a plastic lock nut (usually the same color as the stopcock handle). Tighten or loosen the lock nut to adjust the ease of turning the stopcock.
The glass stoppers should be included with each size.