6.3 Water and Solutions
1. Properties of
water
:
Water is vital to life on
Earth. Its properties
allow it to provide
environments suitable
for life and to help
organisms maintain
homeostasis. Humans
can survive many days
without food, but can
survive only a few days
without water
A
Water is made
up of one
oxygen atom
and two
hydrogen
atoms.
B
Water is polar. Its
bent shape results in
a slightly positive
charge on the
hydrogen atoms and
a slightly negative
charge on the
oxygen. As a result,
it forms hydrogen
bonds with other
water molecules
C
Water is
called the
universal
solvent
because many
substances
dissolve it
.
D
Liquid water becomes
more dense as it cools to
4oC. Yet ice is less dense
that liquid water. As a
result ,nutrients in bodies
of water mix due to
changes in water density
during spring and fall.
Also, fish can survive
winter because ice floats—
they continue to live and
function in the water
beneath the ice.
E
Water is cohesive – the
molecules are attracted
to each other due to
hydrogen bonds. This
attraction creates
surface tension, which
causes water to form
droplets and allows
insects and leaves to
rest on the surface of a
body of water.
F
Water is adhesive – it
forms hydrogen bonds
with molecules on other
surfaces. Capillary action
is the result of adhesion.
Water travels up the stem
of a plant, and seeds
swell and germinate by
capillary action. This
movement also helps the
plant maintain water
pressure to hold itself up.
G
MIXTURES WITH WATER (page 163)
2. What is a mixture?
A mixture is a
combination of
two or more
substances in
which each
substance
retains its
individual
characteristics
and properties.
3. Differentiate the
following terms by
completing the chart:
Term
Definition
Solution A homogeneous mixture in
which one substance is
completely dissolved into
another substance.
Solvent Part of the solution that does the
dissolving
Solute
Part of the solution that gets
dissolved
4. Differentiate
the following
mixtures:
Name
Definition
A few examples
Heterogeneous
mixture
A mixture all the items
are distinct and always
separate
Like items in a salad
Suspension
Particles are mixed, but
overtime will settle out
and separate
Sand in water
Oil and water
Colloid
A mixture in which the
Smoke, fog, mayonnaise, and
particles are not
blood
dissolved in the solvent,
but still will not settle out
and separate.
Solution
A HOMOLOGOUS
mixture in which the
solute is completely
dissolved within the
solvent. It can not be
filtered our and will not
settle out.
Ex. Kool-aid in water
5. What is an Acid?
A substance that will
release Hydrogen ions
when dissolved in
water. The more
Hydrogen ions that are
released, the stronger
the acid.
A
Examples:
hydrochloric acid,
sulfuric acid. Lemon
juice, and vinegar
B
6. What is a Base?
A substance that will release
hydroxide ions (OH-) when
dissolved in water. The more
hydroxide that is released, the
stronger the base.
A
Examples: Baking
soda, Milk of
Magnesia, Liquid
Plumber, Lye and
oven cleaner.
7. Exactly what is the pH Scale?
A system where
Hydrogen – OH sensitive
test strips reveal the
presence and
concentration of Hydrogen
or –OH ions.
8. Sketch
and
label the pH
Scale
9. How do you test for
pH?
You use pH test strips.
Tear you off a piece of the
strip and stick it in your
sample. Then match the
color to the ph Chart. If the
reading is 7 it is neutral. If
it is below 7 it is an acid.
The lower the reading, the
stronger the acid. If the
reading is above 7, it is a
base. The higher the
number the stronger the
base.
10. What does “pH” mean??
This was developed
really long ago. The
exact meaning of the
p has been forgotten.
It is believed to stand
for power and the H
represents hydrogen.
So, pH stands for the
POWER OF
HYDROGEN.
11 .What is a Buffer?
A buffer is slightly
basic. When
mixed with an
acid, the buffer
will neutralize the
acid. Usually, a
salt is produced
as the acid goes
back to a neutral
pH.
12. What does
medicine like Alkaseltzer, Maalox,
Tums, or Rolaids do
for you?
These
medications are
buffers. They
neutralize the
stomach acid
and convert it to
salt and water.
13. What do prescription
medications like zantac,
prilosec, or aciphex do for
you.
These medications
are acid blockers.
They shut down the
glands that produce
stomach acid. They
are not antacids.
14. What does Peptobismuth do for you?
This medication
contains some
antacid. The
main ingredient
in this medicine
is clay. This
medicine coats
the stomach so
the acid can’t get
to the stomach
lining.