Viscosity
Viscosity of Liquids
Part I: Low Viscosities
Mona Kanj Harakeh
1
Objectives
• To measure and analyze the viscosities of ideal (Toluene/p-Xylene) and nonideal (Methanol/Water) binary solutions and their components. • To determine the Activation Energy to viscous flow. • The effect of temperature change on the viscosity will be studied. Method: The viscosities of liquids are determined by measuring the flow time for various liquids in an Ostwald viscometer.
2
Ostwald viscometer
3
Viscosity
• The resistance of
a liquid to flow is called its
viscosity
• Viscosity is a property of liquids that is important in applications ranging from oil flow in engines to blood flow through arteries and veins. Measuring viscosity • How long a liquid takes to flow out of a pipette under the force of gravity. • How fast an object (steel ball) sinks through the liquid under gravitational force.
4
Molecular properties contributing to viscosity
Viscosity arises from the directed motion of molecules past each other, it is a measure of the ease with which molecules move past one another. It is affected by many factors such as: • Molecular size. • Molecular shape. • Intermolecular interactions (attractive force between the molecules). • Structure of the liquid itself. • Temperature(Viscosity decreases with increasing temperature the increasing kinetic energy overcomes the attractive forces and molecules can more easily move past each other).
5
Viscosity
The IUPAC symbol of viscosity is the greek symbol eta “”. Viscosity “η” of a fluid is its resistance to flow. When a Liquid flows, whether through a tube or as the result of pouring from a container. Layers of liquid slide over each other.
The force (f) required is directly proportional to the Area (A) and velocity (v) of the layers and inversely proportional to the distance (d) between them. Av Equ. 1
f
fd gcms cm gcm 1 s 1 1 piose 1P Av cm 2 cms 2
2
d
unit
Part I: Low Viscosities
Mona Kanj Harakeh
1
Objectives
• To measure and analyze the viscosities of ideal (Toluene/p-Xylene) and nonideal (Methanol/Water) binary solutions and their components. • To determine the Activation Energy to viscous flow. • The effect of temperature change on the viscosity will be studied. Method: The viscosities of liquids are determined by measuring the flow time for various liquids in an Ostwald viscometer.
2
Ostwald viscometer
3
Viscosity
• The resistance of
a liquid to flow is called its
viscosity
• Viscosity is a property of liquids that is important in applications ranging from oil flow in engines to blood flow through arteries and veins. Measuring viscosity • How long a liquid takes to flow out of a pipette under the force of gravity. • How fast an object (steel ball) sinks through the liquid under gravitational force.
4
Molecular properties contributing to viscosity
Viscosity arises from the directed motion of molecules past each other, it is a measure of the ease with which molecules move past one another. It is affected by many factors such as: • Molecular size. • Molecular shape. • Intermolecular interactions (attractive force between the molecules). • Structure of the liquid itself. • Temperature(Viscosity decreases with increasing temperature the increasing kinetic energy overcomes the attractive forces and molecules can more easily move past each other).
5
Viscosity
The IUPAC symbol of viscosity is the greek symbol eta “”. Viscosity “η” of a fluid is its resistance to flow. When a Liquid flows, whether through a tube or as the result of pouring from a container. Layers of liquid slide over each other.
The force (f) required is directly proportional to the Area (A) and velocity (v) of the layers and inversely proportional to the distance (d) between them. Av Equ. 1
f
fd gcms cm gcm 1 s 1 1 piose 1P Av cm 2 cms 2
2
d
unit