Exp.4 Determination the Viscosity of Liquids
Theory:
The viscosity of liquid is a resistance to flow of a liquid. All liquids
appear resistance to flow change from liquid to another, the water faster flow
than glycerin, subsequently the viscosity of water less than glycerin at same
temperature. Viscosity occurs as a result of contact liquid layers with each
other. The viscosity is measuring by Ostwald viscometer.
Relative Viscosity is the ratio of the absolute viscosity of the fluid on the
viscosity of water at a certain temperature.……..>>>>>>>>>>>>>. .
The viscosity coefficient is force (dyne) necessary to move the layer of liquid
1 cm2 in speed 1 cm/sec on another layer of liquid and the distance between
them is 1cm.
Equation the Poisellieh :
πr 4 f
η=t
8vl
For two liquids:
η1 f1 t1
=
η2 f2 t 2
Where:
πr4
is constant
8vl
16
, When:
f = gdh
η1 t1 d1
∴ =
η2 t 2 d2
η1 is viscosity of liquid 1.
η2 is viscosity of liquid 2.
t1 flow time of liquid 1.
𝑡2 𝑓𝑙𝑜𝑤 𝑡𝑖𝑚𝑒 𝑜𝑓 𝑙𝑖𝑞𝑢𝑖𝑑 2.
d1 density of liquid 1.
𝑑2 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑙𝑖𝑞𝑢𝑖𝑑 2.
The factors effect on the viscosity:
1. Effect of Temperature: the temperature of the liquid fluid increases its
viscosity decreases. In gases its opposite, the viscosity of the gases
fluids increases as the temperature of the gas increases.
2. Molecular weight: the molecular weight of the liquid increases its
viscosity increases.
3. Pressure: when increase the pressure on liquids, the viscosity increase
because increase the attraction force between the molecules of liquid.
17
Theory:
The viscosity of liquid is a resistance to flow of a liquid. All liquids
appear resistance to flow change from liquid to another, the water faster flow
than glycerin, subsequently the viscosity of water less than glycerin at same
temperature. Viscosity occurs as a result of contact liquid layers with each
other. The viscosity is measuring by Ostwald viscometer.
Relative Viscosity is the ratio of the absolute viscosity of the fluid on the
viscosity of water at a certain temperature.……..>>>>>>>>>>>>>. .
The viscosity coefficient is force (dyne) necessary to move the layer of liquid
1 cm2 in speed 1 cm/sec on another layer of liquid and the distance between
them is 1cm.
Equation the Poisellieh :
πr 4 f
η=t
8vl
For two liquids:
η1 f1 t1
=
η2 f2 t 2
Where:
πr4
is constant
8vl
16
, When:
f = gdh
η1 t1 d1
∴ =
η2 t 2 d2
η1 is viscosity of liquid 1.
η2 is viscosity of liquid 2.
t1 flow time of liquid 1.
𝑡2 𝑓𝑙𝑜𝑤 𝑡𝑖𝑚𝑒 𝑜𝑓 𝑙𝑖𝑞𝑢𝑖𝑑 2.
d1 density of liquid 1.
𝑑2 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑙𝑖𝑞𝑢𝑖𝑑 2.
The factors effect on the viscosity:
1. Effect of Temperature: the temperature of the liquid fluid increases its
viscosity decreases. In gases its opposite, the viscosity of the gases
fluids increases as the temperature of the gas increases.
2. Molecular weight: the molecular weight of the liquid increases its
viscosity increases.
3. Pressure: when increase the pressure on liquids, the viscosity increase
because increase the attraction force between the molecules of liquid.
17
