Isolation of a solid by suction filtration

Select the appropriate size of apparatus based on the amount of solid you expect to isolate and the volume of liquid to be collected ib th receiver flask. Consider the following points  

There is no point in using a large Buchner funnel for a srnall amount of solid since you will collect a layer of solid one molecule thick and be unable to scrape it from the filter paper cleanly. If there is too much solid for the size of the funnel, you will have to repeat the filtration with a second set of apparatus or the solid may not suck dry quickly. 

If you use a side-arm boiling tube to try to collect 100 mL of liquid, you will overfill the tube and liquid (i) will flow into the pressure tubing, contanSTnating it for your fellow students (ii) may fill the intermediate trap, if there is one, and you will need to dismantle and clean it iii) may be sucked into the water pump causing corrosion and loss of performance. 

Clamp the receiving vessel to a support stand pressure tubing is heavy and even large Buchner flasks will fall over do not think that a test tube rack will hold a side-arm boiling tube safely. 

Place the corrict-sized Budtner coiar lb the nick of the receiving flask it should sit well into the neck and fit the funnel to form a good seal. 

---