|What is a hydrophobic, and how would you identify
it (say you were looking at the ingredients on a
Coppertone can)? What chemical reaction takes
place when the hydrophobic wears off?
|Question Date: 2009-05-20|
Hydrophobic is term to describe something that
does not mix with water. Hydrophilic is the term
to describe something that likes water. If this
is to describe an ingredient in sunscreen, this
means that it will not dissolve in water.
Hydrophobic things are oily such as hydrocarbons,
fats and oils. Hydrophilic things will easily
dissolve in water such as salts like phosphates,
sulfates etc. They hydrophobic chemical is
probably used in waterproof sunscreen. This means
the sunscreen will stick more to the oil on your
skin, and won't wash off in water. It will still
wear off your skin over time just by rubbing of
clothing etc, but there is no chemical reaction
taking place.Soap would also be able to wash off
the hydrophobic ingredient.
Hydrophobic just means 'afraid of water'.So
something that is hydrophobicrepels water. Oil is
hydrophobic, therefore oils or Vaseline are put in
lotions or sunscreen to repel water (such as sweat
and pool/ocean water). Silicon is also hydrophobic
so it is sometimes added too. When the lotion
wears off (with lotions it is basically wiped or
rubbed off) their hydrophobic properties are worn
of as well.
Van Der Wall's forces - the electrons are
constantly changing position in any molecule, and
polar molecules that have electric dipoles like to
line up like magnets (and for exactly the same
reason as magnets). Polar molecules will bond to
other polar molecules, non polar to other non
polar, and you'll get separation.
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