soap making

Soap Making

A 20-mule team hauling borax out of the valley. Photo provided by the National Park Service.

Borax (Na2B4O7 _10H2O), the most widespread borate mineral was found to

help remove dirt from people and cloth. Borax is crumbly and powdery, and dissolves easily in water. Borax became an alternative to the very harsh soap

which was used prior to the discovery of borax in the late 1800's. This light and easy to use substance was hailed the world over as a washing, cleansing,

antiseptic, preservative, and medicine miracle. In the 1880s, large borate deposits were discovered in Death Valley,

California. However, the Death Valley borate deposits were located almost 170 miles from the nearest railway. In order to get the borate to the railway

economically, the owners of the Death Valley mines used large wagons pulled by teams of 20 mules. The detergents made from this borate were thus sold

as "20 Mule Team Borax".                                                                                          

A 20 mule team hauling borax in Death Valley

Saponification

glyceryl tripalmitate(tripalmitin)

glycerol 3 sodium palmitate(soap)

CH2 – O – C – (CH2)14CH3

CH – O – C – (CH2)14CH3

CH2 – O – C – (CH2)14CH3

O

O

O

CH2 – OH

CH – OH

CH2 – OH

O

3 Na+ -OC – (CH2)14CH3 3 NaOH+ +

sodiumhydroxide

Process of making soap from animal fat or vegetable oil using a base.

A Phospholipid

polar head

nonpolar tails

(a) chemical structure of a phospholipid

(b) simplified way to draw a phospholipid

polar headnonpolar tails

Timberlake, Chemistry 7th Edition, page 576

A Model of a Cell Membrane

Timberlake, Chemistry 7th Edition, page 587

Polar

Nonpolar

Cholesterol ProteinsPhospholipidbilayer

Formation of a Triglyceride

Stearic Acid

Kelter, Carr, Scott, Chemistry A Wolrd of Choices 1999, page 257

Fatty acidCarboxylic acid group

SoapCOO- bonds to a metal ion (Na+)

Na+

H+ lost from COOH

Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

Sodium stearate:a soap

Sodium dodecylsulfate:

a detergent

Cleaning Action of Soap

Micelle

Timberlake, Chemistry 7th Edition, page 573

Micelle

Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

micelle

Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

SOAP vs. DETERGENT-- made from animal and -- made from petroleum vegetable fats -- works better in hard

water

Hard water contains minerals w/ions like Ca2+, Mg2+, and Fe3+ that

replace Na1+ at polar end of soap molecule. Soap is changed into

an insoluble precipitate (i.e., soap scum).

micelle: a liquid droplet covered w/soap or detergent molecules

Solvation

NONPOLAR

NONPOLAR

POLAR

POLAR

““Like Dissolves Like”Like Dissolves Like”““Like Dissolves Like”Like Dissolves Like”

Solvation

• Soap / DetergentSoap / Detergent– polar “head” with long nonpolar “tail”– dissolves nonpolar grease in polar water

micelle