Unit B –Chapter 2 – Review #1
B-1
1.
Polar Covalent (electron sharing) bonds form. The
Oxygen “hogs” the electron pairs, while
Hydrogen misses out.
2.
A Hydrogen bond – It is a very weak bond but it
creates many of the unique properties of H2O.
3.
The Covalent bond is much stronger than the
Hydrogen bond.
4.
The Oxygen atom in a water molecule takes on a
partly negative field due to the fact that it hogs
the two electron pairs (it is more electronegative)
it is supposed to evenly share.
5.
A polar molecule is any molecule that has a
region that has a bit of a positive charge and a
region that has a bit of a negative charge.
6.
A Hydrogen bond forms between a Hydrogen on
a molecule that is a bit positive and some other
part of a molecule that has a bit more negativity
to it.
7.
Ionic bonds form between a metal and a nonmetal, the metal donates valence electrons while
the non-metal accepts those electrons. So the
metal becomes a positive ion and the non-metal
becomes a negative ion, then the two are drawn
together.
Covalent bonds form between a non-metal and
another non-metal, this bond requires the two
atoms to share a pair/pairs of electrons to meet
the Octet rule. The electron pairs spend time
orbiting both atoms.
B-2
1.
2.
"Universal Solvent".
Other polar molecules and Ionic compounds are
easily dissolved in Water.
3.
The watery portion of blood is important for a
number of reasons: - dissolving key solutes
(nutrients and wastes) for transport.
– Water’s high Specific Heat Capacity, helps the
body with Thermoregulation.
4.
Water is less dense in its solid form, so ice floats.
Also water is transparent to let light through the
vertical column for aquatic producers to
photosynthesize.
5.
Water has a high S.H.C., because of the cohesive
property of water. When you add heat (kinetic
energy) to water, the molecules resist picking up
their kinetic energy because they try to stick
together because of H-bonding between the
water molecules.
6.
A high SHC, allows water to resist temperature
change. Bodies of water (organisms as well as
ponds, lakes oceans etc) resist drastic
temperature change. Organisms perspiring cools
the body by running a phase change. Liquid to
gas – requires lots of energy to be absorbed.
7.
During metabolic reactions heat is always given
off. This heat is moderately absorbed into tissue
fluids and blood and the heat is carried out to the
skin.
8.
Water is unique in that when it solidifies the
molecules spread out during crystallization. This
makes the substance less dense as a solid. So ice
forms at the top of liquid water.
9.
Ice forms at the top of a body of water. If ice was
more dense than liquid, it would form at the
bottom of bodies of water and over many years
all bodies of water would eventually freeze up
solid.
10. Cohesive means that the molecules want to stick
to each other. They are drawn to each other
because of H-Bonding between the different
waters.
This cohesive property of water helps with
transportation, as energy is put into moving some
water it will efficiently pull on the rest of the water.
B-3
1.
When acids dissolve in H2O, H+ ions are released.
It is these reactive hydrogen ions that give acids
their corrosive properties.
2.
When bases dissolve in water, OH- ions are
released. It is these reactive hydroxide ions that
give a base its corrosive power.
3.
A BUFFER.
4.
Acids range from 0 – 6.9 or so on the pH scale.
Examples: stomach acid diluted pH =2.5, Lemon
Juice pH = 2.0, Coca Cola/Vinegar pH = 3.
5.
A pH of 7.0 is NEUTRAL. Distilled water and tears.
This means that there are 10-7 moles of H+ ions
and an equal 10-7 moles of OH- ions. A perfect
balance.
6.
It is a 10 X increase or decrease. For example pH
= 5  10-5 = .00001 moles of H+ while a pH of 4
 10-4 =.0001 moles of H+ ions.
7.
(10). A pH of 6 has 1000 X more H+ ions than a
substance with a pH of 9. 9 8  7 6
X10 X10 X10 = 1000
8.
Bicarbonate ions (HCO3-) can pick up H+ ions
when the pH drops and then form Carbonic acid
H2CO3, This carbonic acid can go to the lungs and
be broken down into H2O and CO2. Which are
then exhaled.
But in this case we want to keep the Carbonic
acid in the blood and let it dissociate into
Bicarbonate ions (HCO3-) and H+ ions. These free
H+ ions will combine with all those extra
Hydroxide (OH-) ions to form H2O.
Multiple Choice
1. D
2. A
3. A
4. B
5. C
6. C
7. D