Instruments that are used in lab, their uses and mechanism

1. Instruments that are used in lab, their uses and mechanism
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1) Condenser: Condenser is an apparatus or container for condensing
vapour. It is an apparatus for reducing gases to their liquid or solid form
by the abstraction of heat.

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Uses of condenser:
i. Condensers are often used in reflux, where the hot solvent vapours of a
liquid being heated are cooled and allowed to drip back. This reduces the
loss of solvent allowing the mixture to be heated for extended periods.
ii. Condensers are used in distillation to cool the hot vapours, condensing
them into liquid for separate collection. For fractional distillation, an air
or Vigreux condenser is usually used to slow the rate at which the hot
vapours rise, giving a better separation between the different
components in the distillate.
iii. Mainly condensers are used in the medicinal chemistry lab in order to
reduce drug loss.
Mechanism of condenser:
A condenser is a piece of laboratory glasswareused to cool hot vapours or
liquids. A condenserusually consistsof a large tube containing a smaller glass
tube running its entire length, within which the hot fluids pass. The ends of
the inner glass tube are usually fitted with ground glass joints, which are
easily fitted with other glassware. During reflux, the upper end is usually left
open to the atmosphere or vented through a bubbler or a drying tube to
prevent the ingress of water or oxygen. The outer glass tube usually has two
hose connections, and a coolant (usually tap water or chilled water/anti-
freezemixture) is passedthroughit. Formaximumefficiency, and to maintain
a smooth and correctly directed thermal gradient so as to minimise the risk
of thermal shock to adjacent glassware, the coolant usually enters through
the lower fitting, and exits through the higher fitting. Maintaining a correct
thermal gradient (i.e. entering coolant at the cooler point) is the critical
factor.

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2) Suctionpump: Itis a pump forraisingsolventbysuction process.Itusually
consist of a cylinder containing a piston fitted with a flap valve.

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It is a common pump in which the liquid to be raised is pushed by atmospheric
pressure into the partial vacuum under a retreating valved piston on the
upstrokeand reflux is prevented by a valve in the pipe that permits flow in only
one direction.
Uses of Suction Pump:
i. Itactually used to accelerate the filtration.
Mechanism:
Suction is the flow of a fluid into a partial vacuum, or region of low pressure.
The pressure gradient between this region and the ambient pressure will
propel matter toward the low pressure area.
A suction pump works by atmospheric pressure; when the piston is raised,
creating a partial vacuum, atmospheric pressure outside forces water into
the cylinder, whence it is permitted to escape by an outlet valve. It actually
used to accelerate the filtration.
Pumps typically have an inlet wherethe fluid enters the pump and an outlet
where the fluid comes out. The inlet location is said to be at the suction
sideof the pump. The outlet location is said to beat the dischargesideof the
pump. Operation of the pump creates suction (a lower pressure) at the
suction side so that fluid can enter the pump through the inlet. Pump
operation also causes higher pressure at the discharge side by forcing the
fluid out at the outlet. There may be pressure sensing devices at the pump's
suction and/or dischargesides which controlthe operation of the pump. For
example, if the suction pressureof a centrifugal pump is too low, a device
may trigger the pump to shut off to keep it from running dry with no fluid
entering.

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3) Buchner funnel: Itis a cylindrical often porcelain filtering funnel that has
a perforated plate on which the filter paper is placed and that is used
usually with a vacuum. It is named after its inventor,
Eduard Buchner (1860–1917), German chemist.

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Uses of Buchner funnel:
i. The main use is to dry crystals after recrystallization.
ii. The Buchner funnel simply speeds up the separation of solid/liquid
mixtures bydrawingoff theliquid under vacuumand catching thesolid
component on a piece of filter paper. This basic concept can save
significant amounts of time compared to the much slower process of
gravity filtration.
iii. The main advantage in using this type of filtration is that it proceeds
much more quickly (severalorders of magnitude) than simply allowing
the solventto drain through the filter medium via the force of gravity.
Mechanism:
A Buchner funnel is a piece of laboratory equipment used in filtration. It is
traditionally made of porcelain, but glass and plastic funnels are also
available. On top of the funnel-shaped part there is a cylinder with a fritted
glass disc/perforated plate separating it from the funnel. A funnel with a
fritted glass disc can be used immediately. For a funnel with a perforated
plate, filtration material in the formof filter paper is placed on the plate, and
the filter paper is moistened with a solvent to prevent initial leakage.
The liquid to be filtered is poured into the cylinder and drawn through the
perforated plate/fritted glass disc by vacuum suction. The suction allows the
wet recrystallized compound to dry out such that the pure dried crystal
compound is left remaining. However, it is often the case that further drying
is required, by an oven or other means, in order to remove as much residual
solvent as possible.

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4) Beaker: Itis a deep wide mouthed thin-walled vesselusually with a lip for
pouring that is used especially in science laboratories.

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Uses of Beaker:
i. Used as a laboratory container and mixing jar.
ii. Used especially in chemistry for holding and measuring liquids.
iii. Container for stirring, mixing and heating liquids.

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5) Measuring cylinder: It is a narrow, cylindrical container marked with
horizontallines to represent units of measurement and used to precisely
measure the volume of liquids.

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Uses of Measuring cylinder:
i. A measuring cylinder is used in a laboratory for measuring exact
quantities of a liquid.
ii. Inthe chemistry laboratory,themeasuring cylinder is used in titration,
a procedure used to determine the concentration of a chemical in a
solution.
iii. Because scientists use them to measure small and large volumes,
measuring cylinders come in different sizes.
iv. The can be used to calculate the density of an object if it’s mass is
known.
v. Measuring cylinders are generally more accurate and precise
than laboratory flasks and beakers.
Mechanism:
Itis important to choose the correctmeasuring cylinder for the volume that
is wishto measure.Itis also importantto takea carefullook atthe graduation
scaleon the measuringcylinder beforeusing it. Ithaveto make surethat one
know which volume is represented by the distance between two adjacent
graduation marks. Always leave the measuring cylinder on a flat surface
when one is reading the volume of the liquid it contains. One should move
one’s body downwards so thatyour eyeis on the same horizontalline as the
surfaceof the liquid. One should not lift the measuring cylinder to measure
the volume of the liquid contained in it.

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6) Conical flask: It is a flask having a wide base, narrow neck and conical
form, convenient in laboratory experimentation for various purpose.

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Uses of Conical flask:
i. Used to heat and store substances.
ii. Used to swirlingliquids by handwithout therisk of spilling and reduces
the loss of the evaporation (because of the narrow neck).
iii. Used to manipulate solutions or to carry out titrations.
iv. Hot vapours condense on the upper section of the Erlenmeyer flask,
reducing solvent loss.
v. Its narrow necks can also support filter funnels.
Mechanism:
In a titration experiments you place the conical flash below the burette and
release the acid into the flask which contains a base and you shakethe flask
to mix throughout the experiment.
Titration experiments are used to find out the amount of acid required to
neutralise the base, and ultimately the concentration of the base.

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7) Litmus paper: Filter paper which has been treated with a natural water-
soluble dye obtained from lichens. The resulting piece of paper, called
'litmus paper'. It is a strip of paper impregnated with litmus used as a
chemical (colour) indicator.

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Uses of Litmus paper:
i. Used as a pH indicator. Blue litmus paper turns red under acidic conditions
(pH below 4.5) while red litmus paper turns blue under alkaline conditions
(pH above 8.3). Neutral litmus paper is purplish in colour.
ii. Wet litmus paper can also be used to test water-soluble gases; the gas
dissolvesin the water and the resulting solution coloursthe litmus paper. For
instance, ammonia gas, which is alkaline, colours the red litmus paper blue.
iii. Chemical reactions other than acid-base reaction can also cause a colour
change to litmus paper. For instance, chlorine gas turns blue litmus paper
white – the litmus dyeis bleached,due to presenceof hypochlorite ions. This
reaction is irreversible, so the litmus is not acting as an indicator in this
situation.
Mechanism:
Used to test for acidity:
Blue litmus paper consists of cellulose filter paper infused with a solution of
litmus dye freshly extracted from lichens.
In an alkaline solution, the hydrogen ion levels are too low to significantly
damagethe chromophore'sdoublebonds,preservingthenaturalblue colour.In
a neutral solution like distilled water, the hydrogen ion levels are significant
enough to begin damaging a significant number of dye molecules. For those
molecules that are affected, the hydrogen-degraded chromophores cause the
dye molecules to turn from blue to red. At the microscopic level, the litmus
paper is a mixtureof unaffected blue molecules and degraded red molecules. To
the observer, however, the paper appeared to be a uniform shade of purple.
Finally, in an acidic solution, the excess of hydrogenions manage to degrade the
vast majority of chromophore double bonds, turning the litmus paper entirely
red.

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Used to test for basicity:
Red litmus paper consists of cellulose paper infused with dye molecules that
have already been degraded by acid (hence the red colour). Red litmus paper
essentially functions as blue litmus paper in reverse.
As a solution's pH increases, the concentration of hydrogen ions decreases but
the concentration of hydroxide ions [OH-] increases. These negatively-charge
ions "steal" hydrogen atoms from the degraded dye molecules to form water.
The dye molecule respond to the lost hydrogen by forming double bonds
between their carbon and oxygen atoms.Inthis way, thedyemolecule "rebuild"
their electron networks and regain their original blue colour.
8) Pipette:Itisa smallpieceof apparatuswhichtypically consistsofa narrow
tube into which fluid is drawn by suction (as for dispensing or
measurement) and retained by closing the upper end.

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Uses of Pipette:
i. Used to measure or transfer a quantity of a liquid.
Mechanism:
In a way, pipettes work a lot like drinking straws in that they allow liquids to be
'sucked-up'into one end. Though they may work like drinking straws, never use
yourmouth to suck-upliquidsinto a pipette! Insteadusea pipette-aide. Pipette-
aides or pipettors aresuction devices that are used to either suck liquids into or
expel liquids out of pipettes. For some types of measurements it may be
necessary to expel, or blow-out, the total liquid volume from the pipette using
the pipette-aid. A pipette is calibrated with a series of graduation lines to allow
the measurement of more than one volume. Measure using the bottom of the
concave surface of the liquid in pipette. Most of our work is done with sterile
pipettes and if so, theoperations aredoneaseptically. When workingwith non-
sterile pipettes it is a good idea to workaseptically anywayasa matter of routine
in order to practice the technique.
1. Without opening the sterile sleeve, look through the wrapper and check that
the pipette is calibrated as a 'blow-out'pipette. Also make surethat the tip
is not crackedor chipped and check the wrapperhasn'tbeen damaged in any
way.
2. Open the wrapper and remove the pipette aseptically and insert the top,
wide end into a pipette-aide.
3. Fill the pipette a bit abovethe capacity line desired and then slowlylower the
meniscus to that capacity line.
4. Remove the pipette from the vessel, allowing the outside of the pipette to
gently touch the inner lip of the vesselto removeany adherent liquid. Don't
touch the tip of the pipette though to avoid introducing an air bubble.
5. Aseptically move the pipette to the receiving vessel and deliver the
contents. If you are pipetting a volume between two measurement lines
you will not have to 'blow-out'. However if you are delivering the entire
contents of the pipette you will haveto 'blow-out'the remaining liquid in the
tip with a firm puff of air from the pipette-aide.
6. Remove the pipette aseptically and discard it into an appropriate discard
container.

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9) Test tube: A cylindrical tube of clear glass, usually open at one end and
rounded at the other, used as a container for small amounts of a
substance in laboratory tests and experiments.

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Uses of Test tube with mechanism:
i. Test tubes are used by chemists in the lab to heat, hold and mix small
quantities of liquid or solid chemicals during experiments.
ii. Test tubes haveclear glass to allow monitoring and observationduring
an experiment.
iii. A test tube with a stopper is used to store samples and for other
storage purposes.
iv. The test tube is made of specialized glass so it can be heated and
cooled without breaking.
v. Their round bottom and straight sides minimize mass loss when
pouring, make them easier to clean, and allow convenient monitoring
of the contents.
vi. The long, narrow neck slows down thespreading of vapours and gases
to the environment.
vii. A test tube filled with water and upturned into a water-filled beaker is
often used to capture gases, e.g. in electrolysis demonstrations.

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10) Round bottom flask: A glass flask used in a laboratory for holding
chemical liquids and solutions, which has a spherical shape for uniform
heating, and one or more long cylindrical necks.

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Uses of Round bottom flask:
i. Round-bottom flasks are used to contain chemical reactions run by
chemists, especially for reflux set-ups and laboratory-scale synthesis.
ii. The round-bottom flask is used for reactions, distillations and
collection.
iii. It is used for uniform heating and boiling of liquid.
Mechanism:
Round-bottom flasks are types of flasks having spherical bottoms used as
laboratory glassware, mostly for chemical or biochemical work. They are
typically made of glass for chemical inertness and in modern days, they are
usuallymade of heat-resistantborosilicateglass.Thereis atleast one tubular
section known as the neck with an opening at the tip. Two or three-necked
flasks are common as well. Round bottom flasks come in many sizes, from5
mL to 20 L, with the sizesusuallyinscribed on the glass. Becauseof the round
bottom, cork rings are needed to keep the round bottom flasks upright.
When in use, round-bottomflasks arecommonly held at the neck by clamps
on a stand.