Polarity of Solvents. A Hydrocarbon Typical petroleum product Non-polar CH 2 CH 3 CH 2 CH 3 C 18 H 38.

A Hydrocarbon

• Typical petroleum product

• Non-polar

CH2 CH2

CH2CH3 CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3

C18H38

Oil and Water Don’t Mix

• Oil is nonpolar• Water is polar

“Like dissolves like”

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 470

Hydrogenation

Timberlake, Chemistry 7th Edition, page 570

+ H2

vegetable oils shortening stick margarine

tub (soft)margarine

heat, nickel catalyst

Molecular Polarity

H–C–H

H

H–C–H

H–C–H

H–C–H

H

H H

O

nonpolar molecules: -- e– are shared equally-- tend to be symmetric

e.g., fats and oils

polar molecules: -- e– NOT shared equallye.g., water

“Like dissolves likeLike dissolves like.”polar + polar = solutionnonpolar + nonpolar = solutionpolar + nonpolar = suspension (won’t mix evenly)

Using Solubility Principles

C=CCl

ClCl

Cl

Chemicals used by body obey solubility principles.

-- 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

-- water-soluble vitamins: e.g., vit. C

Used,FilteredPerc

Perc Storage/Collection

Distiller

Pressing

Water Discharge

Air toAtmosphere

DirtyClothes

FinishedClothes

DirtyPerc

Perc

Warm VaporFrom Dryer

CondensedLiquid Perc

CleanPerc

CollectedUsedPerc

HazardousWaste* *Soil, dirt, unrecovered Perc

NewPerchloro-ethylene

(PERC)

Filter

Separator

Condenser

Dry Cleaning Unit-One unit washes and dries

Washing Process

Drying Process

Process used forWash and dry

MODEL OF A SOAP MOLECULE

NONPOLARHYDROCARBON

TAIL

POLARHEAD

Na1+

emulsifying agent (emulsifier): -- molecules w/both a polar AND a nonpolar end-- allows polar and nonpolar substances to mix

detergent lecithin eggse.g., soap