An overview:
A volumetric pipette is a thin glass tube
used to measure liquid substances to pour into something like a beaker or a
flask while conducting an experiment. The pipette is so thin that it becomes
practically impossible to put liquid into it with hands. The person using the
pipette has to suck the liquid up into the pipette by putting its one end in
the liquid and the other end in his mouth or with pipettor. The measurement of
the pipette is somewhat different from the other measurement apparatuses
available in a laboratory. There is a zero mark on the pipette body which is
the indication that the liquid below it should not be taken into the
experiment. The pipettes come in different capacities to measure liquids in
various experiments as well chemical processes.
The Structure:
The pipette
as discussed earlier has two openings. From one end the liquid enters into it
in and then it is kept in by blocking that end with the help of a finger placed
in place of a mouth. There is a bulb like structure present in the middle of
the pipette’s body which is round in shape. This structure increases the
capacity of the body along with making the suction safe as some amount of
chemical can be held in this part of the apparatus . Most of the chemicals are
harmful in nature and there intake can cause serious health problems, so the
presence of the bulb slows down the pace of the liquid moving up so that the
person using it can control and remain safe from swallowing the liquid. The
pipettes are available in different capacities ranging from 1ml to 100 ml. One can also order specific
sizes of pipette if requirement is different than pipettes available in the
market. The bulb in large pipettes will be large in size to increase the
capacity of it in terms of holding the liquid..
Guidelines
to use:
Certain points have to be kept in mind before anyone starts
the experiment with the help of the pipette. The temperature has to be under
control for getting the best results from the pipette. It is very important
that the pipette being used in any experiment has to be clean and dry. If the
pipette is wet, then make sure to fill the pipette with some liquid which is
going to be used in the experiment, and this liquid should be thrown away.
After filling the pipette at the time of performing the experiment, make sure
that there are no air bubbles at the upper end of the liquid. While working
with a pipette lower meniscus is taken into consideration. The reading should
be taken by keeping the pipette at eye level so the exact reading is taken and
the pipette is filled completely up to the upper limit or marking.
The volumetric pipette
comes in great use while doing volumetric analysis, for example Saponification.
Pipettes are one of the most important requirements for
these kind of experiments.
