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Polarity of Solvents.

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Presentation on theme: "Polarity of Solvents."— Presentation transcript:

1 Polarity of Solvents

2 A Hydrocarbon Typical petroleum product Non-polar C18H38 CH2 CH2 CH2

3 Oil and Water Don’t Mix Oil is nonpolar Water is polar
“Like dissolves like” Lycopodium Powder demonstration. Lycopodium powder is a nonpolar hydrocarbon that doesn’t mix with water. It is dry to the touch and not oily feeling. Sprinkle lycopodium powder on top of a beaker of water. Slowly, push your finger through the surface of the lycopodium powder into the water. Slowly withdraw your finger, it remains dry the entire time. Why? Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 470

4 Hydrogenation + H2 shortening stick margarine tub (soft) margarine
vegetable oils + H2 FOOD SUBSTITUTES “Chemistry is widely used in the food industry to manufacture new convenient foodstuffs and to check for impurities. Butter is known as a saturated fat, whereas most vegetable oils, which are normally liquid, are polyunsaturated fats. They can be changed to solids, such as margarine, by a chemical process called hydrogenation – the addition of hydrogen to the oils using a catalyst. Hydrogenation makes the oil more like butter and easier to spread. Margarine was first developed in the 1860’s in France as a cheap butter substitute.” Eyewitness Science “Chemistry” , Dr. Ann Newmark, DK Publishing, Inc., 1993, pg 7 heat, nickel catalyst Timberlake, Chemistry 7th Edition, page 570

5 Molecular Polarity H nonpolar molecules: -- e– are shared equally
H–C–H H nonpolar molecules: -- e– are shared equally -- tend to be symmetric e.g., fats and oils H O polar molecules: -- e– NOT shared equally e.g., water “Like dissolves like.” polar + polar = solution nonpolar + nonpolar = solution polar + nonpolar = suspension (won’t mix evenly)

6 Using Solubility Principles
Chemicals used by body obey solubility principles. -- water-soluble vitamins: e.g., vit. C -- fat-soluble vitamins: e.g., vits. A, D Dry cleaning employs nonpolar liquids. -- polar liquids damage wool, silk -- also, dry clean for stubborn stains (ink, rust, grease) -- (tetra) perchloroethylene is in common use C=C Cl

7 One unit washes and dries
Dry Cleaning Unit- One unit washes and dries Washing Process Drying Process Process used for Wash and dry Pressing Dirty Clothes Air to Atmosphere Warm Vapor From Dryer Dirty Perc Filter Condenser Perc Used, Filtered Perc Separator New Perchloro- ethylene (PERC) Condensed Liquid Perc Finished Clothes Perc Storage/ Collection Clean Perc Collected Used Perc Water Discharge Hazardous Waste* Distiller *Soil, dirt, unrecovered Perc

emulsifying agent (emulsifier): -- molecules w/both a polar AND a nonpolar end -- allows polar and nonpolar substances to mix e.g., soap detergent lecithin eggs MODEL OF A SOAP MOLECULE Na1+ NONPOLAR HYDROCARBON TAIL POLAR HEAD

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