Water Properties Lab - Hudson City School District

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Transcript Water Properties Lab - Hudson City School District

Water Properties Lab
Water is Polar Covalent
Hydrogen Bonds
• Weak
• Attraction of water to water
What forms a drop?
• Cohesion causes water to form drops
• surface tension causes them to be nearly
• adhesion keeps the drops in place.
Surface Tension
• Water attracts itself and pulls in to form a
“film” on its surface to form a drop.
• Attraction of water to an unlike substance
• (like glass)
• Note the drop is flatter than on wax paper
Water Drop Shapes
• Water cohesion to itself
and forms a nice, round
• Round drop on wax
paper (not strong
adhesion to water).
• As adhesion to glass is
stronger + pulls the
water, it makes a flatter
On wax paper
On glass
Water on wax paper
• Plain wax paper
Soapy wax paper
You can break surface tension
with soap.
Polar coheres to Polar not
• Water (Polar) has no
adhesion to the wax
(nonpolar) paper. It
would roll right off.
• Water has more
adhesion to a glass
Climbing Property of Water
• Colors are
separated by
densities. Less
dense colors go
to the top.
• Black is composed
of all the colors.
Capillarity – water climbs up small
• The small spaces
(pores of the paper)
provide adhesion to
the water.
• The water makes a
column by cohesion
to itself.
Adhesion to paper
Cohesion of water to water
Oil is hydrophobic
• Oil and water do not mix.
Oil is on
Water is
on bottom
Food coloring dissolves in water.
Water is polar.
Food coloring is polar.
Oil is nonpolar (no charge).
Oil has no hydrogen bonding.
• Polar molecules dissolve
polar molecules.
Stirring oil and water
• The oil will go back to being
separate from the water.
Oil sheen on water (oil on top of
water in a thin layer)
Getting rid of oil on water
• Detergent
breaks up the
oil into very
small droplets.
HowStuffWorks "How do you clean
up an oil spill?“ (pick a video)
Burn Off
Slick Sack
• Absorbent
Hand washing
Oil Spills
dead sea life
human life
cost of cleanup
• molecules have (hydrophobic)
and to attract oil structure,
but also have a region that is
polar (hydrophilic) attracts
water to wash it away.
Like detergent.