The stronger the intermolecular stronger forces the

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Unformatted text preview: w and internal and may be thought of as a measure of fluid friction. The stronger the intermolecular stronger forces, the higher the viscosity. higher Higher temperature lower Higher temperature, lower viscosity Surface Surface Tension Surface Tension: the resistance of a liquid to increase the the surface area. Surface Surface Tension Surface Tension: the Energy required to increase the surface per unit area (J/m2). Surface molecules are only attracted inwards the bulk molecules. Internal Internal (bulk) molecules are equally attracted in all directions. Spheres have the smallest surface area for their volume A rain drop at a hydrophobil surface Rain Rain drops on a spider-web spider- Surface Surface Tension Surface Tension of water: 7.29×10-2J/m2 Surface Tension of mercury: 4.6×10-1 J/m2 The stronger intermolecular forces; the higher surface tension. U-shaped meniscus meniscus Surface tension (cohesive forces) < adhesive forces rounded meniscus meniscus Surface tension (cohesive forces) > adhesive forces Capillary Capillary Action Cohesion is the intermolecular attraction between like molecules Adhesion is an attraction between unlike molecules Phase Phase Changes Phase change (state changes): The transformation from one physical physical state to another. Whenever the phase change involves going to a less ordered state, the energy must be supplied to overcome the intermolecular forces. Phase Phase Diagram •Critical Point: critical T and critical P beyond which liquid and critical critical gas are indistinguishable. Triple point: the temperature and pressure at which all three states exist in equilibrium. Critical Temperature Pressure Critical Temperature & Pressure Every substance has a critical temperature ( Tc ), above which its gas critical ), can’t be liquefied, no matter how great the applied pressure is. Critical temperature(Tc): the highest T at which a highest substance can exist as a liquid liquid Critical pressure ): lowest ( Pc ): the lowest P required for the liquid to exist at critical temperature Critical Phenomenon Critical Phenomenon The separate phases of CO2 Increasing the T f...
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