Essential Chemistry: Water

Report
By Chris Witzigman
Tom Cunningham
Gabe Fonseca
Truths about Water
1.
2.
3.
4.
5.
6.
Water molecules are
cohesive and form
hydrogen bonds
Water molecules are
adhesive and form
hydrogen bonds with polar
surfaces
Water is a liquid at normal
physiological
temperatures
Water has a high specific
heat
Water has a high heat of
vaporization
Water’s greatest density
occurs at 4 degrees
Celsius.
Situation A
 During the winter, air
temperatures in the
northern United States
can remain below 0°C for
months; however, the
fish and other animals in
the lakes survive.
 http://www.bbc.co.uk/le
arningzone/clips/life-ina-frozen-lake/10467.html
 Water has a high specific
heat
 Keeps the water below
the ice layer on top
warm
Situation B
 Many substances- for
example salt (NaCL) and
sucrose- dissolve quickly
in water.
 Water is adhesive and
forms hydrogen bonds
with polar substances
 The water creates a
hydration shell around
Na+ and Cl- atoms thus
dissolving them.
Situation C
 When you pour water
into a 25-ml graduated
cylinder, a meniscus
forms at eh top of the
water column.
 This is the property of
adhesion.
 The water is attracted to
the glass and so clings to
the side of the
graduated cylinder and
dips in the middle. This
creates the meniscus.
Situation D
 Sweating and the
evaporation of sweat
from the body surface
help reduce a human’s
body temperature.
 This is water’s heat of
vaporization
 The water on the surface
of your skin heats up
first and then
evaporates leaving the
cool water behind and
pulling the hot water
away, leaving the surface
cooler
Situation E
 Water drops that fall on a
surface tend to form
rounded drops or beads.
 This is the property of
cohesion
 The polar water
molecules create
hydrogen bonds and
stick together in beads
 This is the property of
adhesion
 The water is polar and
tends to stick to polar
surfaces
Situation F
 Water drops that fall on
your car tend to bead or
round up more after you
polish or wax your car.
 This is the property of
cohesion
 The polar water
molecules create
hydrogen bonds and
stick together in beads
 The wax is non polar
and so the wax and
water repel each other
creating more beading
Situation G
 If you touch the edge of a
paper towel too a drop of
colored water, the water
will move up into (or be
absorbed by) the towel.
 This is water’s property
of capillary action.
 Water is attracted to the
paper fibers by adhesion
and is pulled up
through the towel and
because water creates
hydrogen bonds to itself
it pulls more water
molecules behind it.

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