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Hydrophobic and hydrophilic forces are interactions that serve to keep chemical

groups positioned close to one another. Hydrophobic is water-repelling and Hydrophilic is

water-loving.

Hydrophobic interactions are created because of the uncharged nature of the involved

chemical groups. An example of such a chemical group is CH. All the bonds around the

carbon atom are occupied. !he chemical group is described as being non-polar. !hus" a water

molecule#a polar molecule#is unable to establish an association with the non-polar

chemical group. !his tends to create instability in the network of water molecules" and so is

undesirable. !he repulsive force of the surrounding water molecules acts to force

hydrophobic regions into an association with like regions. !he effect tends to be theformation of a hydrophobic $pocket$ or $envelope$ in a protein or a carbohydrate molecule or

matrix. How soap works is a good explanation of hydrophobic and hydrophilic. !here two

ends on a molecule of soap. %ne of them is hydrophilic end and that end loves the water but

keeps away from hydrocarbons" &A molecule that only contain hydrogen and carbons'" and

the oils and fats. !he other part is hydrophobic and keeps away from the water but grabs on

to the dirt and oil" etc. !hen the oil and fats" etc. can be easily washed away. Hydrophilic

interactions are possible with polar chemical group. (ater is polar because oxygen is far

more electronegative than hydrogen and thus the electrons involved in an oxygen-hydrogen

bond spend more time in proximity to the oxygen atom. )ecause of this une*ual electron

sharing" the oxygen atom takes on a partial negative charge and the hydrogen atom a partial

positive charge. +n addition" the bonds in a water molecule cancel each other out. %ther polar

groups can then form ionic type bonds with water.

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,ome examples of Hydrophilic are water" milk" soap" wool" hair" and cellulose &the

main constituent of paper" wood" and cotton'. ,ome of the examples of Hydrophobic are oil"

waxes" fats" all fatty acids" and the hydrophobic end of the soap.

,urfactants" or surface active agents" are amphiphilic molecules that contain a polar

head group and a non polar tail group" as shown in igure . !he hydrophobic group is

typically a linear or branched alkyl chain while the head group of the surfactant molecule can

be either a non ionic" cationic" or anionic group. )ecause of the distinct differences between

these regions of the molecule" surfactants like to reside at interfaces.

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!he structure of a surfactant molecule has two distinct parts. !he hydrophilic head is

polar and likes to come into contact with an a*ueous phase. !he hydrophobic tail is non polar

and resists interactions with an a*ueous phase.

/eference

. http011www.nnin.org1education-training1k-2-teachers1nanotechnology-

curriculum-materials1water-race-hydrophobic-3

2. https011researchthetopic.wikispaces.com1!he4difference4between4hydrophobi

c4and4hydrophilic45art42. http011www.encyclopedia.com1doc162-73893329:.html

7. http011www.che.ufl.edu1unit-ops-lab1experiments1;icelles1;icelles-

manual237.pdf