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Solids and Liquids Physical Properties of Liquids.

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Presentation on theme: "Solids and Liquids Physical Properties of Liquids."— Presentation transcript:

1 Solids and Liquids Physical Properties of Liquids

2 Physical Properties of Liquids Condensed matter: Atoms or molecules are closely packed and interact with each other Atoms or molecules do not interact with each other, except for collisions

3 Physical Properties of Liquids Liquids have a permanent network of intermolecular bonds that are continuously made and broken liquids hold together liquids can flow

4 Physical Properties of Liquids flow: the ability of a liquid to move and change shape under a force, such as gravity.

5 Physical Properties of Liquids On the molecular level, liquids are like amorphous solids. Energy of solid vs. liquid However, higher energy in liquids causes intermolecular bonds to break quickly after they are formed.

6 Physical Properties of Liquids Quartz a crystalline form of SiO 2 Glass an amorphous form of SiO 2 Liquid SiO 2 doesn’t remember whether it came from quartz or glass! slow coolingfast cooling

7 Physical Properties of Liquids Quartz a crystalline form of SiO 2 Glass an amorphous form of SiO 2 Liquid SiO 2 doesn’t remember whether it came from quartz or glass! melting

8 Physical Properties of Liquids Cohesion Physical properties The property of a liquid that causes it to hold together Attractive forces between molecules in a liquid cause liquid drops to come together as tight as possible in a perfect sphere

9 Physical Properties of Liquids Cohesion Cohesion keeps rain drops together as they fall on the ground Liquid mercury (Hg) is very cohesive

10 Physical Properties of Liquids Cohesion Adhesion Physical properties The property of a liquid that causes it to stick to surfaces Geckos use the property of adhesion to stick to surfaces such as the walls and ceilings of houses

11 Physical Properties of Liquids Adhesion When something is “wet,” we mean that liquid is adhering to it Different surfaces have different wettability : they can be wet by the same liquid differently

12 Physical Properties of Liquids Adhesion When something is “wet,” we mean that liquid is adhering to it Different surfaces have different wettability : they can be wet by the same liquid differently Liquids that adhere to things very well are called adhesives They are commonly used as glues or put onto tape to make it sticky

13 Physical Properties of Liquids Cohesion or adhesion? Water is more adhesive It sticks to the sides of the glass Mercury is more cohesive It sticks to itself more Meniscus

14 Physical Properties of Liquids Plants use capillary action to draw water up from roots to leaves. Even very tall trees move water this way. Water passes through these tubes capillary action: an effect where liquids is pulled up a thin tube by adhesion

15 Physical Properties of Liquids Cohesion Adhesion Viscosity Physical properties The resistance of a liquid to flow under an applied force Honey

16 Physical Properties of Liquids Viscosity Viscosity is a measure of resistance to flow. Snails and slugs use mucus, a very viscous substance, to help them stick to surfaces and move.

17 Physical Properties of Liquids Viscosity Viscosity depends onthe strength of intermolecular bonds Water is a polar molecule with strong intermolecular forces. Water is more viscous than nonpolar liquids, such as liquid nitrogen

18 Physical Properties of Liquids Viscosity Viscosity depends onthe strength of intermolecular bonds the shape of the molecules Oils are more viscous because the long-chain molecules can be easily entangled, and this slows down the flow

19 Physical Properties of Liquids Cohesion Adhesion Viscosity Surface tension Physical properties A property of liquids to resist having their surface broken

20 Physical Properties of Liquids surface tension: a property of liquids to resist having their surfaces broken, usually measured in J/m 2. Surface tension measures the energy it takes to break the surface of a liquid.

21 Physical Properties of Liquids Surface tension Soaps work by partially lowering surface tension Soaps are medium-length chains with - one polar end - and one non-polar end The polar end adsorbs to the water surface, and this breaks up the surface tension

22 Physical Properties of Liquids Cohesion Adhesion Viscosity Surface tension Liquids have a permanent network of intermolecular bonds that are continuously made and broken This results in interesting physical properties:


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