Burettes and pipettes are both used to measure fluids in laboratories, but for different purposes. Burettes are stationary and only dispense fluids, while pipettes are mobile and can withdraw and dispense fluids. They have different filling mechanisms and graduations, with pipettes being better suited for smaller volumes. Burettes are typically used for titrations, while pipettes are preferred for measuring and delivering liquids to other containers.
While both burette and pipette instruments are used by laboratory analysts to take accurate measurements of fluids, they are used for different purposes. A burette is typically stationary equipment, while a pipette is mobile. Pipettes can both withdraw and dispense fluids, while a burette only dispenses fluids. Commonly, an analyst fills a burette from the top, while a pipette is filled from the bottom up. Both pieces of equipment have graduations for measuring precise volumes of fluid, but pipettes tend to be better suited to smaller volumes than burettes.
One major difference between a burette and a pipette is that a pipette is held in the hand and a burette is typically secured in a stand on the laboratory bench. Both are long, thin hollow tubes designed to hold liquids. A burette is often made of glass, while a pipette is often available in plastic and glass versions.
Since hollow tubes are basically measuring devices, both a burette and a pipette have markings along the side to signal when there is a particular volume of fluid inside the tube. Because laboratory analysts hold pipettes in their hands, pipettes tend to have smaller volume capacities than a burette, which can be larger as it sits stationary on the lab bench. The way a burette is filled with liquid is another difference between a burette and a pipette.
Burets have an open top on the tube and a small exit point at the other end of the tube, which is closed off with a stopcock. An analyst then pours the liquid into the burette on top, until the required volume marker is reached. A pipette, on the other hand, does not have a stopcock locking mechanism, but is an open hollow tube with a tapered end.
Pipettes require a suction device at the top end, which alters the pressure within the tube to draw liquid through the tapered end from a container of liquid. As long as the suction pressure remains on the pipette, the liquid remains inside the tube. When the suction is removed, the liquid falls out, as the lower end of the tube does not have a mechanical locking system like the burette.
Typically, a burette and a pipette are used for different purposes in laboratory procedures. The burette dispenses precise volumes of liquid into another container, as in a titration. When an analyst titrates two substances, he analyzes how much of one substance is needed to make a visually recognizable change in the other substance.
The changes in appearance versus volume of the liquid can be used to calculate the concentrations of certain components in the sample substance. Pipettes can also be used in titrations, but because they hold less liquid and may require refills, the burette is more time-efficient. Conversely, because burettes are cumbersome to use, pipettes are the preferred mode of measuring liquids and delivering liquids to other containers.
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