Chemistry for Changing Times
12th Edition
Hill and Kolb
Chapter 21
Household Chemicals:
Helps and Hazards
John Singer
Jackson Community College, Jackson, MI
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History of Cleaning
Many years ago and even today in the third
world, clothes are cleaned by beating on rocks
in a river or stream. Some plants such as
soapworts or soapberries contain saponins,
which produce a soapy lather. Wood ashes
contain potassium and sodium carbonate, which
form alkaline solutions in water with some
detergent properties. Sodium carbonate is still
sold today as washing soda.
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Fat + Lye → Soap
Soap is made by reacting animal fat or
vegetable oil with lye (NaOH).
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Fat + Lye → Soap
Soap works because one end of the molecule is
hydrophilic (water attracting) and the other end
is hydrophobic (water repelling).
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Fat + Lye → Soap
The hydrophobic “tail”
dissolves into oil,
leaving the
hydrophilic “head” on
the outside. This
spherical structure is
called a micelle.
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Fat + Lye → Soap
Oil and water form an emulsion, with the soap
acting as the emulsifying agent. Any
substance, such as soap, that stabilizes the
suspension of nonpolar substances in water is
called a surfactant (surface-active) agent.
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Fat + Lye → Soap
Disadvantage of Soap
Water that contains calcium, magnesium, and
iron ions is called hard water. These ions will
react with and precipitate soap, reducing its
effectiveness.
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Fat + Lye → Soap
Water Softeners
Additives such as washing soda (Na2CO3 . 10
H2O) and trisodium phosphate (TSP = Na3PO4)
will raise the pH of water and precipitate calcium
and magnesium ions.
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Fat + Lye → Soap
Water Softeners
Water softening tanks
are also used in
homes and
businesses. They
contain a polymeric
material that hold the
calcium, magnesium,
and iron ions and
exchange them with
sodium ions.
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Synthetic Detergents
During World War II, the raw materials for soap
production became scarce. Synthetic
detergents were developed with cleansing
action similar to soap, but without the negative
effects of hard water.
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Synthetic Detergents
ABS Detergents: Nonbiodegradable
The first synthetic detergents were
alkylbenzenesulfonates (ABS) detergents.
Unfortunately, they are nonbiodegradable and
produced a foam that appeared on natural lakes
and rivers as well as in wells and sewage
treatment plants. ABS detergents were banned
and replaced by biodegradable detergents.
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Synthetic Detergents
ABS Detergents: Nonbiodegradable
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Synthetic Detergents
LAS Detergents: Biodegradable
Linear alkylsufonates (LAS) detergents have
linear chains of carbon atoms that can be
broken down by microorganisms.
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Laundry Detergent Formulations
Laundry detergents contain a variety of
compounds designed for specific
functions. These compounds are classified
as surfactants, builders, and
brighteners.
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Laundry Detergent Formulations
Surfactants emulsify the soil and oils. They can
be either anionic, cationic, nonionic or
amphoteric.
Amphoteric surfactants carry both a positive
and negative charge on the same molecule. A
betaine is an example of an amphoteric
surfactant.
CH3(CH2)nCH2NH2+CH2COO© 2010 Pearson Prentice Hall,
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Laundry Detergent Formulations
Builders are added to detergent formulas to
increase the detergency of the surfactant.
Examples include sodium citrate (Na3C6H5O7),
sodium tripolyphosphate (Na5P3O10), and
sodium hexametaphosophate. These
compounds act by causing the sequestration of
the calcium and magnesium ions.
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Laundry Detergent Formulations
Phosphate builders
increase the
eutrophication of lakes.
Some states have
banned their use.
Zeolites trap calcium
and magnesium ions in
a cage-like structure.
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Laundry Detergent Formulations
Brighteners are added to detergent
formulations to make clothing appear bright and
new.
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Laundry Detergent Formulations
Liquid laundry detergents have captured much
of the market in recent years. Liquid laundry
detergents can either be built formulations with
sodium citrate, sodium carbonate, or zeolites, or
they can be unbuilt formulations high in
surfactants and have no builders.
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Dishwashing Detergents
Liquid dishwashing detergents, for
handwashing, usually contain one or more
surfactants, such as LAS or cocamido DEA
[CH3(CH2)nCON(CH2CH2OH)2].
Dishwashing detergents for automatic
dishwashers are usually strongly alkaline. They
can contain sodium tripolyphosphate, sodium
carbonate, sodium metasilicate, and a bleach,
along with a small amount of surfactant. Sodium
hydroxide may also be present.
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Fabric Softeners: Quaternary
Ammonium Salts
Quaternary ammonium salts with two long
alkyl chains are used as fabric softeners. They
attach to clothing fibers, forming a layer one
molecule thick, which gives the clothing a
smooth flexible softness.
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Laundry Bleaches: Whiter
Whites
Bleaches are oxidizing agents that react with
colored stains on fabrics. The more common
bleaches are chlorine bleaches containing
sodium hypochlorite (NaOCl). Oxygenreleasing bleaches contain either sodium
percarbonate (2 Na2CO3 . 3 H2O2) or sodium
perborate (NaBO2 . H2O2). These bleaches
liberate the oxidizing agent hydrogen peroxide in
hot water.
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All-Purpose Cleaning Products
A number of all-purpose cleaning products are
commonly found in the home. These include
household ammonia solutions, baking soda, and
common vinegar.
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Special-Purpose Cleaners
Toilet bowl cleaners are usually acidic materials to remove
calcium carbonate deposits.
Scouring powders contain abrasive materials like silica
(SiO2). They may also contain a surfactant and bleach.
Glass cleaners contain isopropyl alcohol, ammonia, and
sometimes vinegar.
Drain cleaners usually contain sodium hydroxide to saponify
grease. Some contain bits of aluminum that react with the
NaOH to release hydrogen gas to agitate the clog. Many
contain bleach to degrade hair.
Oven cleaners contain NaOH to cut the greasy material on
oven walls.
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Organic Solvents in the Home
Organic solvents are
available for removing
paint, adhesives,
waxes, and other
materials. Most are
volatile and
flammable.
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Paints
Paints include lacquers,
enamels, varnishes, oilbased coatings, and waterbased finishes. They are
composed of three basic
ingredients: a pigment,
binder, and solvent.
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Waxes
Waxes are esters of long-chained fatty acids
and long-chained alcohols. Paraffin wax is a
mixture of long-chained hydrocarbons. Waxes
serve both plants and animals as protective
coatings. Many natural waxes are being
replaced by silicones.
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Cosmetics
The U.S. Food Drug and Cosmetic Act of 1938
defined cosmetics as “articles intended to be
rubbed, poured, sprinkled, or sprayed on,
introduced into, or otherwise applied to the
human body or any part thereof, for cleansing,
beautifying, promoting attractiveness, or altering
the appearance…” The main difference between
drugs and cosmetics is that drugs must be
proven “safe and effective” before they can be
marketed.
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Cosmetics
Skin Creams and
Lotions
Cosmetics are
applied to the dead
cells of the corneal
layer of the skin.
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Cosmetics
Skin Creams and Lotions
A lotion is an emulsion of oil
droplets dispersed in water.
A cream is an emulsion of
water droplets dispersed in
oil.
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Cosmetics
Skin Creams and Lotions
The oily substance of the cream or lotion forms a protective
film over the skin that retains moisture.
Emollients protect the skin by coating and softening it.
Moisturizers hold moisture to the skin.
Humectants, such as glycerol or lactic acid, actually attract
water to the skin.
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Cosmetics
Sunscreen Lotions
Sunscreen lotions work by blocking shortwavelength (UV-B) radiation, but allowing the less
harmful long-wavelength (UV-A) radiation to pass.
Older formulations contained paraminobenzoic acid
(PABA), which is water-soluble. Newer formulations
contain octyl methoxycinnamate (OMC), which is
insoluble in water. Skin protection factor (SPF)
tells how long you can stay in the sun compared to
no protection. I.e., an SPF of 15 means that you can
stay in the sunlight 15 times longer than with no
protection. Sunblocks contain opaque powders like
zinc or titanium oxide that block all UV radiation.
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Cosmetics
Lipsticks and lip balm are similar to skin
creams or lotions in make up and function.
They contain oil and a wax and work by
holding moisture against the skin.
Eye makeup is used to accentuate and
decorate the eyes. They typically contain
waxes, soaps, fats, oils, and pigments.
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Cosmetics
Deodorants and Antiperspirants
Deodorants contain perfume to mask body odor
and a germicide to kill odor-causing bacteria.
Antiperspirants may contain perfumes and
germicides, but also contain compounds such as
aluminum chlorohydrate [Al2(OH)5Cl . 2 H2O],
which are astringents that constrict the pores of
sweat glands to prevent perspiration.
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Toothpaste
Toothpaste is perhaps
the most important
cosmetic product.
Toothpastes are typically
composed of a detergent
and an abrasive. In
addition, there are
flavoring agents, coloring
agents, sweeteners, and
thickeners.
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Perfumes, Colognes, and
Aftershaves
Perfumes may contain many ingredients. Their
components are divided into three “notes”. Notes are
categories of volatility. The first note is the most volatile
fraction and the third or end note is the least volatile
fraction. The end notes often have musky odors.
Colognes are perfumes that have been diluted with alcohol
or alcohol/water mixtures.
Aftershave lotions are similar to colognes, but contain a
higher percentage of alcohol. Some contain menthol or an
emollient.
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Hair Chemistry
Shampoos contain a detergent
such as sodium dodecyl
sulfate. They can also contain
coloring agents, fragrances,
and proteins for repairing split
ends.
Conditioners are mainly longchained alcohols or quaternary
ammonium salts that coat the
surface of the hair and allow
the strands to slide past each
other.
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Hair Chemistry
Hair color is determined by two pigments,
melanin (brownish-black) and phaeomelanin
(red-brown). Hair color can be lightened by
oxidizing with hydrogen peroxide or changed by
dying.
Hair treatment like Grecian Formula® contains
lead acetate [Pb(CH3COO)2]. The lead ions
penetrate the hair shaft and react with the sulfur
to form black lead sulfide.
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Hair Chemistry
Perms are accomplished by
breaking the disulfide bonds
in the proteins with reducing
agents, such as thioglycolic
acid. The hair is then curled
on rollers and treated with
hydrogen peroxide to
reestablish new disulfide
linkages.
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Hair Chemistry
Hair sprays are resins that form a sticky film to
hold the hair in place. A mousse is simply a foam
that contains such a resin.
Hair removers are called depilatories. Most
contain a strongly basic soluble sulfur compound
that attack the peptide bonds in the hair so that it
can be washed off.
Hair restorers, such as Rogaine®, contain
Minoxidil. Minoxidil was first used as a treatment
for high blood pressure. It has the ability to grow
fine hair when it is applied to any skin where hair
follicles are located.
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The Well-Informed Consumer
Many companies spend a lot of money on
advertising their products and the most
expensive product is not always the best. It is
worth the effort to be informed about the
products that you buy and use.
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