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A burette is a lab device used in analytical chemistry for the dispensing of variable, measured amounts of a chemical solution.
Burettes come in two main categories:
- Volumetric burette: delivers measured volumes of liquid.
- Weight burette: delivers measured weights of liquid.
Consist of a specially designed burette, fitted with a flat bottom flask, which contains the solution. Filling the burette is done by pumping air inside the burette flask by squeezing a small bulb pump and covering the lower air vent with your finger.
Uses a small computer to measure and release exact amounts of solution. They are generally screwed on a large bottle, which is filled with the desired liquid/solution.
Consists of a long glass tube, with a glass or PTFE stopcock at one end. Filling the burette is done manually, from the top, or in case of thin burettes, using a rubber bulb to draw liquid from the end, in a similar way to pipettes.
Burettes should be cleaned often to prevent the capillaries from clogging up.
For safety reasons, burettes should always be kept filled with a liquid, most often distilled water, when not in use or covered, usually to limit dust or other contamination. This is not required for automatic burettes.