DETERMINATION OF VISCOSITY OF LIQUID USING OSTWALD’S VISCOMETER

Aim : To determine the viscosity of the liquid by suing Ostwald’s viscometer
Requirements: Chemicals: Distilled water, ethanol, acetone.
Apparatus: Ostwald viscometer, electronic balance, stopwatch.
Principle: Ostwald viscometer is used to determine the viscosity of Newtonian fluid, when the fluid flow by gravity time required by liquid to pass between mark A and B. The time of flow of fluid under test is compared with the time required for the liquid of know viscosity. The viscosity of unknown liquid η1 can be determined using following equation.

η1 =ρ1t1/ ρ 2t2. η2

Where
η1= Viscosity of unknown liquid.
η2= Viscosity of known liquid.
ρ1 = Density of unknown liquid.
ρ2 = Density of known liquid.
t1 = Time of flow of unknown liquid.
t2 = Time of flow of known liquid.
Procedure: Viscometer was mounted in vertical position on a suitable stand, water was filled in the viscometer up to mark A. Then time was counted for water to flow from mark A to mark B. The same procedure was repeated for the test liquid by using the above formula of viscosity of the test liquid can be determined.
Observation table:

Report: The viscosity of unknown liquid was found to be________________