Aim: To determine the viscosity of the given liquid sample using viscometer.
Principle: Viscosity is the index of resistance of a liquid to flow. viscosity is define as force of fraction between two layers of liquid moving passed one another with different velocity the higher the viscosity of liquid moving passed one another with different velocity of a liquid, greater will be the resistance of the flow.
The unit of viscosity is poise. it is also expressed in centi-pose or mili-pose
poise is define as force require to produce a velocity of 1cm/sec between two parallel planes of liquid each 1cm sq in area ad separated by a distance of 1cm.
Ostwald's viscometer can also be called as capillary viscometer. Here when a liquid flows through a capillary tube the time required for the liquid to pass between the two marks is determined.
Procedure:
Determine of purity :
- Take a specific gravity bottle which is clean and dry. Take the weight of empty specific gravity bottle.(W1)
- Fill the specific with distilled water up to its brim. place the lid and wipe he outer surface of the bottle with blotting paper. Weigh the specific gravity bottle with water(W2).
- Remove the distilled water from the bottle.
- Carefully fill the given liquid sample up to the brim. place the lid, dry the outer surface with a blotting paper. Weigh the bottle(w3)
Density:
Weight of specific gravity bottle(W1)
Weight of specific gravity bottle+ water(W2)
Weight of specific gravity bottle+ liquid sample(W1)
Density of the water : 0.9961g/cc
Determination of viscosity:
Ostwald viscometer was taken and cleaned with water and acetone. Viscometer was fixed to a stand in a vertical position.known quantity of water 15l or 20ml) was transfer with the help of pipette through wide limb. Now water was sucked through the other limb up to a level higher than the upper mark 'A' and Clamp the rubber tube with finger to stop the flow of water was allowed to flow down . Stop clock was started when the water level first passes the upper mark 'A' when the water level pass down lower mark 'B' Repeat this process for the given sample twice and calculate time of flow.
Observation :
Time of flow of water (t1) = sec
Time of flow of sample liquid (t2) = sec
Report:
The density of the given liquid sample was found to be
The viscosity of the given liquid sample by using ostwald viscometer was found to be
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