Aula #15 · 2020. 4. 23. · Intermolecular Forces Liquids and Solids & transport properties...
Transcript of Aula #15 · 2020. 4. 23. · Intermolecular Forces Liquids and Solids & transport properties...
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Aula #15
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Intermolecular Forces Liquids and Solids
& at the surface
Surface tension ….is the amount of energy required to stretch or increase the surface of a liquid by a unit area.
Strong intermolecular forces > High surface tension
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Surface tension ….is the amount of energy required to stretch or increase the surface of a liquid by a unit area.
Strong intermolecular forces > High surface tension
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Strong intermolecular forces > High surface tension
SurfactantSodium Laureth Sulfate
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Change of the surface tension.. Presence of a surfactant
SurfactantSodium Laureth Sulfate
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Strong intermolecular forces > High surface tension
SurfactantSodium Laureth Sulfate
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Surface tension ….is the amount of energy required to stretch or increase the surface of a liquid by a unit area.
Bubble pressure tensiometer
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Intermolecular Forces Liquids and Solids
& at the surface
Capillarity Cohesion is the intermolecular attraction between like molecules
Adhesion is an attraction between molecules in a different surface
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Intermolecular Forces Liquids and Solids
& at the surface
Capillarity Cohesion is the intermolecular attraction between like molecules
Adhesion is an attraction between molecules in a different surface
![Page 10: Aula #15 · 2020. 4. 23. · Intermolecular Forces Liquids and Solids & transport properties Viscosity is a measure of a fluid’s resistance to flow. Shearing flow is opposed by](https://reader031.fdocuments.us/reader031/viewer/2022012012/6140a5662e263e64232a328d/html5/thumbnails/10.jpg)
Intermolecular Forces Liquids and Solids
& at the surface
Capillarity Cohesion is the intermolecular attraction between like molecules
Adhesion is an attraction between molecules in a different surface
![Page 11: Aula #15 · 2020. 4. 23. · Intermolecular Forces Liquids and Solids & transport properties Viscosity is a measure of a fluid’s resistance to flow. Shearing flow is opposed by](https://reader031.fdocuments.us/reader031/viewer/2022012012/6140a5662e263e64232a328d/html5/thumbnails/11.jpg)
Capillarity Cohesion is the intermolecular attraction between like molecules
Adhesion is an attraction between molecules in a different surface
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Intermolecular Forces Liquids and Solids
& at the surface
Wetting (molhabilidade)
Contact angle,
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Intermolecular Forces Liquids and Solids
& transport properties
Viscosity is a measure of a fluid’s resistance to flow.
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Intermolecular Forces Liquids and Solids
& transport properties
Viscosity is a measure of a fluid’s resistance to flow.
Shearing flow is opposed by friction between adjacent layers of fluid (which are in relative motion).A force is required to sustain the motion of the upper plate. The relative strength of this force is a measure of the fluid’s viscosity.
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Intermolecular Forces Liquids and Solids
& transport properties
Viscosity is a measure of a fluid’s resistance to flow.
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Intermolecular Forces Liquids and Solids
& transport properties
Viscosity function (dynamic viscosity over shear rate):
1 ... Newtonian liquid
2 ... shear-thinning substance
3 ... shear-thickening substance
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Intermolecular Forces Liquids and Solids
& transport properties
Viscosity temperature /pressure dependence
EQUATION
Vogel–Tammann–Fulcher (VTF)
Viscosity pressure
Viscosity temperature
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Intermolecular Forces Liquids and Solids
& transport properties
Viscosity type of flow
In laminar flow, molecules move in orderly layers,
while in turbulent flow they follow no pattern
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Intermolecular Forces Liquids and Solids
& transport properties
Viscosity type of flow …. Reynolds NUMBER Re
In laminar flow, molecules move in orderly layers,
while in turbulent flow they follow no pattern
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