Some Consumer Chemistry
What’s in that stuff and why does it
work?
Why do we need soap?
• Oil and water don’t mix! (Why?)
• To make them mix (so we can wash
the oil away) we use a molecule that
has an end that attracts water
(hydrophilic) and an end that attracts
the non-polar oil (hydrophobic).
• Soaps are salts of the fatty acids
(organic) that make up lipids.
Soap in
Action
Grease
Tail (hydrophobic) end
of soap molecule
attracts grease
Head (hydrophilic) end
of soap molecule
attracts water
The problems with soap…
• Hard water contains
Mg2+, Ca2+, and/or Fe3+
ions.
• The soap molecule
reacts with these ions
and form a
precipitate…soap scum!
Soap Alternatives…
• Detergents are synthetic
molecules that have
hydrophobic and hydrophilic
ends like soap but do not form
the insoluble materials with
hard water ions.
• Most modern cleaning
products (hand soap,
shampoo, toothpaste…) are
detergents.
Detergent additives
• You want your clothes white and bright,
right?
• Textiles tend to fade or turn yellow over
time.
• Manufacturers add products that make
you think the clothes are brighter and
whiter.
• Bluing agents (whiteners) absorb yellow
light so the clothes don’t look yellow.
• Brighteners absorb UV light and emit it as
visible light so the clothes look brighter.
Detergent additives
• Enzymes remove protein-based stains by
breaking the protein molecules so the
trapped colored molecules can be
released. They also “chomp” small
broken fibers from natural materials.
• Oxygen releasing materials (bleaching
agents) have an oxidizing effect and
convert colored compounds to colorless
ones.
Fabric Softeners
• Fabrics feel rough because of small broken
fibers on the cloth.
• Fabric softeners use a lubricating substances
that provide a smooth feel and reduce static
electricity build-up.
Toothpaste
Toothpastes contain one or more of the following:
• Detergent - to remove grease/oil
(sodium lauryl sulfate)
• Basic compound – to neutralize acid formed by
bacteria (CaCO3 or baking soda and ammonia)
• Abrasive – to remove material deposited on the
mineral tooth surface (silicates…like sand)
• Coloring agents – to make the toothpaste white
(titanium dioxide) or other interesting colors
Toothpaste
Toothpastes contain one or more of the following:
• Fluoride – to produce a harder mineral called
hydroxyfluoroapatite from tooth enamel; this is
usually sodium fluoride (Fluoristat)
• Flavoring and sweetening agents – so we will use
toothpaste! Sweeteners are artificial, not
sucrose!
• Bleaching agents – to whiten teeth
(hydrogen peroxides or related compounds but
not bleach)
Sweeteners
• Sucrose (table
sugar) – naturally
derived from plants
such as sugar cane
and beets
• Aspartame (Equal®)
– combination of
two amino acids
slightly modified
Sweeteners
• Saccharin (Sweet ‘N
Low®) – artifically
produced
• Sucralose (Splenda®)
– derived from
sucrose with chlorine
atoms replacing OH
groups
Sweetners
• Stevioside (Truvia®) –
naturally derived from the
stevia plant
Relative Sweetness
Sweetner
Sucrose
Fructose
Maltose (Malt Sugar)
High fructose corn syrup
Aspartame
Saccharin
Sucralose
Stevioside
Relative Sweetness
100
140
30-50
120-160
18000
30000
60000
25000-30000
Sunscreens
• Contain molecules that absorb and/or reflect
some UV-A and UV-B rays
• Sun Protection Factor (SPF)
• Argh!
• SPF indicates how much longer it will take for
skin to redden…An SPF factor of 15 means
that it will take about 15 times longer to get
red when exposed…if applied correctly!
Sunscreens
SPF
2
% UV absorbed
50
4
70
8
87.5
15
93.3
30
96.7
50
98
Drug Name
Concentration, %
Absorbance
Aminobenzoic acid
Up to 15
UV-B
Avobenzone
2-3
UV-A I
Cinoxate
Up to 3
UV-B
Dioxybenzone
Up to 3
UV-B, UV-A II
Ecamsule*
2
UV-A II
Ensulizole
Up to 4
UV-B
Homosalate
Up to 15
UV-B
Meradimate
Up to 5
UV-A II
Octocrylene
Up to 10
UV-B
Octinoxate
Up to 7.5
UV-B
Octisalate
Up to 5
UV-B
Oxybenzone
Up to 6
UV-B, UV-A II
Padimate O
Up to 8
UV-B
Sulisobenzone
Up to 10
UV-B, UV-A II
Titanium dioxide
2 to 25
Physical
Trolamine salicylate
Up to 12
UV-B