Experiment
Object:
Determination
of
molecular weight of polymer by Oswald viscometer.
Theory:
Polymer
Polymers
are the large molecule made by the hundred of the monomers joint to form a long
chain
The
word polymer comes from greek word
poly means many and mers
means form.
Monomers
Small
molecles
which combine together to form polymer molecule are known as monomers
Viscosity
Viscosity is
an another type of bluck
property defne as
liquid to flowwhen intermolecular attraction are strong
within a liquid there are larger viscosity.
Factor affecting the viscosity:
Temperature:
Viscosity
decrease with the rise of temperature in a liquid 2% per degree. The gases
increase with the rise of temperature.
Size
and Shape of the Molecules:
Liquids
have bigger size of the molecules will have high viscosity.
Elongated
molecule of the liquid have more resistance to flow as compare to spherical
molecules. Hence elongated molecule will have high viscosity.
Intermolecular
Forces of Attraction:
Greater
the intermolecular attraction in liquid, greater will be viscosity of liquid.
Oswald’s Viscometer:
Viscometer
is an instrument measuring the viscosity of the liquid.
1.Oswal
method
is a simple method of viscosity, in which the viscosity of the liquid measured
by comparing the viscosity of unknown liquid withb that
of the liquid whose viscosity is known. In this method viscosity of the liquid
measure by comparing the flow of times of two liquids of equal volumes using
same viscometer
2.The
molecular weight of polymer is measured by using viscometerand the mplecular
weight is obtained by this technique called viscosity average molecular weight
3.The
molecular weight of the polymer is very high so the
viscosity of the polymer is very high compaired to
the pure solvent
Apparatus:
Oswald
viscometer
Stop
watch
Beaker
50ml
Iron
stand
Clip
with rubber band
Reagents:
Water
Solution
of unkown
composition
Procedure:
1. Oswald
viscometer is cleaned by the mixture of hot chromic acid and sulphuric acid
and its washed by the help of distilled water
2. Rinse
it with alcohol and dry it
3. Fill
the viscometer with 10ml of water than it until water reached at mark A
4. Start
the stop watch and note downthe time
until the water reached at mark B
5. Note
the time of flow of water
6.
Repeat the same procedure twice for water
7. Now
repeat the procedure for given dilutions of solution
8. Plot
the graph between the concentration VS reduced viscosity
Observation:
  Result:
The molecular weight of polymer is -------------------------.
Pdf File: https://www.termmate.com/rabia.aziz/ostwald-viscometer-lab-experiment-Wfh3Gj |
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