- Water And Ph Chemistry Worksheet
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2
3
4Chapter 2 – Water and pH
Water - one of the most important molecules in life.
70% of the bodies mass is water
•
2/3 of total body water is intracellular (55-66% body weight of men and 10% less for women)
•
The rest is interstitial fluid of which 25% is in the blood plasma.
•
pH - The body tightly controls both the volume and pH of water.
The bicarbonate system is crucial for blood maintenance
•
changes of pH greater than 0.1 are dangerous and can lead to coma -diabetics
•
Properties of water
Polarity
•
Hydrogen bonding potential
•
Specific heat, heat of vaporization
•
It
i s
t he
u nique
c ombination
o f
p roperties
o f
w ater
Nucleophilic
•
that
m ake
i t
t he
p erfect
s olvent
f or
b iological
Ionization
•
systems.
W e
w ill
d iscuss
e ach
o f
t hese
p roperties
i n
Water is an ideal
•
more
d etail.
biological solvent
Water is close to a tetrahedral shape with the unshared
3
electrons on the two sp
-hybridized orbital are in two corners and the
hydrogen in others
o
Compared to a tetrahedron, CH
(109
) or NH
the bond angle is smaller
4
3
o
o
o
(109.5
and 107
vs.104.5
)
Water has hydrogen
bonding potential
•H-bonds are non-covalent, weak
interactions
•H
O is both a Hydrogen donor and acceptor
2
•One H
O can form up to four H-bonds
2
What Are the Properties of Water?
A comparison of ice and water, in terms of H-bonds and Motion
Ice: 4 H bonds per water molecule
•
Water: 2.3 H bonds per water molecule
•
Ice: H-bond lifetime - about 10 microsec
•
Water: H-bond lifetime - about 10 psec
•
(10 psec = 0.00000000001 sec)
•
The Solvent Properties of Water Derive from Its Polar Nature
•
Water has a high dielectric constant
•
Ions are always hydrated in water and carry around a "hydration shell"
•
Water forms H bonds with polar solutes
The Solvent Properties of Water Derive
from Its Polar Nature
What makes this molecule important?
solvent ability - easily disrupts ionic compounds - dielectric constant (D) is
high (measure of the ability to keep ions apart)
Large electronegativity creates a strong ionic type
–
bond (dipole).
Liquid water has a higher density than solid water
–
(ice). Is this normal? Think of why this is important?
orderliness - solvating shells
–
ability to take place in many hydrogen bonds (up to
–
4 at a time)
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