Polarity of Solvents

1
Polarity of Solvents
2
A Hydrocarbon

• Typical petroleum product
• Non-polar

CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH3
CH2
CH2
CH2
CH3
CH2
CH2
CH2
CH2
CH2
C18H38
3
Oil and Water Dont Mix

• Oil is nonpolar
• Water is polar
• Like dissolves like

Zumdahl, Zumdahl, DeCoste, World of Chemistry
2002, page 470
4
Hydrogenation
H2
heat, nickel catalyst
Timberlake, Chemistry 7th Edition, page 570
5
Molecular Polarity
nonpolar molecules -- e are shared
equally -- tend to be symmetric
e.g., fats and oils
polar molecules -- e NOT shared
equally e.g., water
Like dissolves like. polar polar
solution nonpolar nonpolar solution polar
nonpolar suspension (wont 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
7
Dry Cleaning Unit- One unit washes and dries
Pressing
Dirty Clothes
Air to Atmosphere
Warm Vapor From Dryer
Dirty Perc
Condenser
Filter
Perc
Used, Filtered Perc
Separator
Finished Clothes
Condensed Liquid Perc
New Perchloro- ethylene (PERC)
Perc Storage/ Collection
Collected Used Perc
Clean Perc
Water Discharge
Hazardous Waste
Distiller
Soil, dirt, unrecovered Perc
8
emulsifying agent (emulsifier)
-- molecules w/both a polar AND a nonpolar end
-- allows polar and nonpolar substances to mix
detergent
lecithin
eggs
e.g., soap
MODEL OF A SOAP MOLECULE
Na1
NONPOLAR HYDROCARBON TAIL
POLAR HEAD