Soap
Soap
• Known to exist in 2800 BC
• Mt. Sapo: animal fats + wood ashes or kelp, +
clay + heat  good cleaning mixture = soap +
glycerine
• This is the saponification reaction.
• Plant or animal fat + alkali + heat  K or Na
salts of fatty acids.
• Clow p 116-117
Chemical Reaction
• http://chemistry.about.com/library/weekly/bl
sapon.htm
How do soaps function?
• Soaps are
– K or Na salts of fatty acids
– Soluble in water.
– Surfactants or surface active agents which lower the
surface tension of water; “wets” water.
– Negatively charged.
– Basic; can react with acid stains, dirt.
– Fatty acid tail (long carbon backbone with H atoms) is
attracted to oils and fats.
– Acid end is attracted to water
Soap in the Industrial Revolution
• Soap production remained a domestic activity
until the end of the 18th c. I.e. the industry
developed slowly.
– Not a component of a natural resource.
– Product of chemical reaction which had to be
analyzed, tested and reproduced.
– Great variety of starting materials were a source
of confusion (Dundonald again, p. 118; record his
contributions to various chemical industries).
Soap Industry
• Once the science ( chemical reaction, required
reactants, desired products, conditions) was
understood, the soap industry grew (Clow p
119) from 1830 (Clow graph p. 124).
• Clow p. 120 diagram
• Chemistry rules (Clow p 125, 126, 127)
The Fermentation Industry
An Introduction: Distillation and
Brewing
Alcohol
• Alcohol describes a broad class of organic
compounds that contain the –OH functional
group, know as the hydroxyl group.
• The smallest alcohol is methyl alcohol or
methanol
– From the alkane methane = CH4
– Also called wood alcohol since it is the major product
of the fermentation of wood
– CH3OH
– Poisonous when ingested
Alcohol
• The next smallest is ethyl alcohol of ethanol
– From the alkane ethane C2H6
– also called grain alcohol since it is produced when
grain ferments
– C2H5OH
– Is the alcohol present in alcoholic drinks
• There are many other alcohols: propanol,
butanol, etc
From Grain to Alcohol
Chemical Reaction
• (C6H10O5)n + nH2O  (C6H12O6)n
Starch from cellulose (plant matter) is converted to
glucose via hydrolysis or addition of water. Methods
include the action of enzymes (major commercial
method) and reaction with acid (historic method)
• C6H12O6  2C2H5OH + 2CO2
Glucose or sugar decomposes to ethanol and
carbon dioxide in the presence of yeast and
absence of oxygen (anaerobic oxidation). This
is called fermentation.
Combustion of Sugar
Chemical Reaction
• In the presence of oxygen, sucrose burns to
give water and carbon dioxide.
C6H12O6 + 6O2  6H2O + 6CO2
A Comparison
Beer
Wine
Spirits
Historical Reference 7000 BC
6000 BC
3000 BC
Water
Water
Water
Water
Fermentable
Material (e.g.)
Starch: Malted
barley
Sugar: Grapes,
other fruits
Distilled fermented
grapes, grain, etc
Brewer’s Yeast
Yeast
Distillation
Flavorings
Hops
Other grapes
Orange, hazelnut
Usual ABV (alcohol
by volume)
4-6% AVB
10-14% ABV
30-95%
Other
pH = 2.9-3.9
tartaric, malic, citric
Ideal Liquid Solution
• Phase diagram for “ideal” 2-component liquid
system.
– http://www.chemguide.co.uk/physical/phaseeqia
/idealpd.html#top
– Fractional distillation can lead to 100%
purification.
– http://www.chemguide.co.uk/physical/phaseeqia
/idealfract.html#top
– Wikipedia on Benzene-Toluene Phase Diagram
Benzene and Toluene Form an
Ideal Solution
• Benzene boils at 80.1 oC and toluene at 110.6
oC.
• The B-B IMF are nearly the same as the T-T
IMF and also the B-T IMF; these are the
conditions for an ideal solution.
• Benzene and Toluene can be separated
completely by fractional distillation – note
different BPs. Which boils first?
Benzene and Toluene Phase Diagram
and Separating two Components
Why 95% ABV?
• Phase diagram for water and alcohol (non
ideal).
– Water boils at 100 oC and ethanol at 78.4 oC.
– Water and ethanol form a low boiling azeotrope at
78.1 oC and 95.6% ethanol and 4.4% water.
– Limit to separation by fractional distillation
Water-Ethanol Phase Diagram
• http://serc.carleton.edu/files/NAGTWorkshop
s/petrology/teaching_examples/Kitchen_Text.
pdf