Using a Buret
LAB TECHNIQUE - USING A BURET
A BURET is a piece of equipment that is used for titration. It is a long cylinder with a valve at the bottom. Unlike a graduated cylinder, which is used to measure the volume of liquid put in, a buret is used to measure the volume of liquid removed. Also a buret, is incremented from top to bottom. (Reading a buret is explained at the end of the page.)
Introduction to Titrations
Titration, a type of volumetric analysis, is a method commonly used in chemistry to figure out the amount or concentration of a chemical in a solution. A chemical reaction is utilized between a solution with an unknown concentration (called an analyte) and a solution with a known concentration (called a titrant or standard solution). Titrations use a buret to carefully measure out small amounts of solutions accurately so the volume of the titrant added can be used to determine the concentration of the analyte. Acid-base reactions are utilized frequently in titrations but oxidation-reduction reactions and precipitate reactions can also be used to determine the concentration of a solution.
Endpoint and Equivalence Points in Titrations
The terms endpoint and equivalence point often get used to mean the same thing but these two terms can refer to slightly different points in a titration. The endpoint of a titration is the point at which an color change, often from an indicator added to the reaction signals that reaction is complete. Indicators are usually added to acid-base titrations to detect the equivalence point, but they are often not exact. The equivalence point is the point in the reaction where the amount (or moles) of titrant neutralizes the amount (or moles) of analyte.