Unformatted text preview: Water and the Fitness of the
Chapter 3 Chapter 3 Page 1 : Properties of Water
s Water molecules are polar and hydrogen bond to
each other. This bonding is responsible for the
special properties of water
special s The properties of water are as follows: s Cohesion = water molecules stick together as a
result of the partial charge attractions between
the hydrogen and oxygen. This is one reason
plants can transport water against gravity. Chapter 3 Page 2 : Properties of Water Cont.
s Adhesion = clinging of one substance to another. In plants
the water molecules cling to the sides of the vessels helping
transport against gravity. This is also seen in glass
graduated cylinders in the lab Ex meniscus
graduated s Surface tension = level of difficulty involved in breaking or
stretching the surface of a liquid
stretching s High specific heat = this means how successfully a
substance resists changing temperature
substance What Is Specific Heat??????? Again
s The amount of amount of heat that must be
gained or lost to change the temperature of 1
gram of a substance by 1° C.
gram s Water absorbs a lot of heat before its temp rises s Why???????? Surface Tension is holding me up! Chapter 3 Page 4: Properties of Water Cont.
s High heat of vaporization = it takes a great
amount of energy to convert water from liquid to
gas. This helps moderate earth’s climate in the
case of water.
case s Water expands when it freezes; it becomes less
dense and floats
dense s Water is a solvent; many substances dissolve in it Chapter 3 Page 5 : Acids and Bases
s Hydrophobic = repelled by water; mostly non polar
substances s Hydrophilic = water loving or attracted to water. Most of
these compounds are polar or charged.
these s Acid = substance which increases the H ion in a solution s Base = substance which accepts H ions or donates OH.
Bases reduce the H ion concentration of a solution.
s pH = negative log of the H ion concentration.
pH declines as H ion concentration increases
and increases as H ion concentration decreases
and The Formulas: pH = - log [H+]
pOH = - log [OH-]
s Chapter 3 Page 6 : Acids and Bases Cont.
s pH scale is logarithmic. This means for every unit of
increase or decrease, the ion concentrations change by a
factor of 10 s the pH scale runs from 0 -14. Seven is neutral. Less than
seven is acid and greater than seven is base
seven s you can use the concentration acid or base to determine
the corresponding concentration because
[H] x [OH]
14 Chapter 3 page 7 : Acids and Bases Cont.
s Buffers are substances that minimize chances is the H ion
or OH ion concentration
or s Ex Human Blood pH range 7.35 -7.45 optimum humans
can only survive blood pH of 7 or greater than 7.8 for a
few s Buffers work by accepting excess H ions and donating H
ions when depleted. It can in practice also occur with
donation of OH we won’t get into that here
Buffers are extremely essential in biological systems
Buffers s Chapter 3 Page 8: Acid Rain
s Normal rain pH = about 5.6 s Acid rain = any pH below that s Ecological damage of great proportions is occurring in
Europe and in some of our high altitude systems.
Europe Acidification of seawater and coral reefs s Reduction in carbonate ions in seawater s Study by Langdon indicates coral reef
calcification decreased bt acidification What is the pH of a liquid that has a
[H] of 0.0001
3 Problem Solving:
s What is the [ H+ ] of an acid that is pH 5?
of s What is the pH of a substance with an
[OH-] of 0.0000001?
[OH s The pH in your fish bowl was 12 yesterday.
You put in acidifier and measure the pH
today. It is now 8. What is the H difference?
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- Fall '07
- pH, Acid rain, ion concentration