Technique: Filtering [edit]

[edit] About Filtering

There are two main reasons to use filtering techniques. One is to filter out solid particles from a liquid so that the liquid will be free from particulate matter, and the other is to separate a solid from a liquid so that the solid can be used in some further way or be dried and then its mass determined in order to find % yield. It is therefore, important for a person to use proper filtering techniques in order to obtain either the maximum amount of solid material present or to maximize the removal of undesirable solid from a liquid. There are two main ways of filtering that are used in high schools; gravity filtration and vacuum filtration. Gravity filtering is the most common in high school labs and it uses regular glass funnels with long stems and various grades of filter paper. Sometimes a Buchner funnel will be used along with a side-arm filter flask connected by rubber tubing to a source of a vacuum.