Water: Adhesion Property

Properties of Water
Chapter 2
Water: Adhesion Property
Adhesion: an attraction between
molecules of different substances
Capillary action – water tends to climb up
straws, or similar (glass)
Meniscus- water makes a curve when
sitting in a graduated cylinder- (glass)
Wet jeans
Mini-lab: Capillary Action
Place the tiny tube in the colored water
and watch it climb…
Does it end up lower or higher than the
outside fluid level?
Can you see the meniscus in the
graduated cylinder?
Water: Cohesion Property
Cohesion: attraction between molecules
of the same substance
Insects can walk on water
Water forms droplets on certain surfaces
(glass, copper, paraffin)
Surface tension
Mini-Lab: Quicker Picker upper
Pour 5 mL of water on your desk. Take
the papertowel and place only the very
end in the pool of water.
Once it stops climbing, measure how far
the water climbed.
Wipe up the desk
Mini-Lab :surface tension
Take a small paperclip and float it in a
beaker of water
What is the trick to doing this?
Mini-Lab: cohesion
How many drops of water can you fit on
a penny?
What shape does the water make?
Why does the water eventually spill
Water is polar, which means the atoms
have slight charges, which makes it
attract itself and other substances, too.
That bond is a hydrogen bond and it is
really weak
WHY is water polar? Because of the 8
protons in the nucleus, the Oxygen has
a stronger attraction for electrons than
hydrogen (in other words they share
Other polar compounds?
NH3 ammonia
HF hyrdogen fluroride
Water is more polar than any other
so it will tend to dissolve ionic compunds,
and other polar substances very well
Alcohol is also polar,
so it does mix with water, but its has a
lower degree of polarity,
 so it won’t dissolve some things that water
OIL- is non-polar
Why does ice float?
Why is that soooooo important to our
The story:
Alcohol doesn’t freeze at the same
temperature as water…so why did I get in
so much trouble?!
Water is an exception to many rules
It freezes from the top down
It becomes less dense when frozen solid
Because the hydrogen bond pattern created
“pockets of open space” making it less dense or
lighter…see bubbles?? In ice??
It ‘s boiling point is too high for its size
It’s freezing point is too low for its size
The normal pattern for most
compounds is that as the
temperature of the liquid
increases, the density
decreases as the molecules
spread out from each other.
As the temperature decreases,
the density increases as the
molecules become more
closely packed. This pattern
does not hold true for ice as
the exact opposite occurs.
In liquid water each molecule
is hydrogen bonded to
approximately 3.4 other water
molecules. In ice each each
molecule is hydrogen bonded
to 4 other molecules.
The End…..