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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
