Download HS-SCI-APC -- Chapter 16- Acid-Base Equilibria

WHAT'S AHEAD
16.1
Acids and Bases: A Brief Review
We start by reviewing the Arrhenius definitions of
acid and base.
16.2
Bmnsted-Lowry Acids and Bases
We then learn the more general Brensted-Lowry
definitions for acid and base. A Bnmsted-Lowry
acid is a proton donor and a Bnmsted-Lowry base
is a proton acceptor. Two species that differ by
the presence or absence of a proton are known as
a conjugate acid-base pair.
16.3 The Autoionization of Water
We will see that the autoionization of water
produces small concentrations of H 30+ and OHions. The equilibrium constant for autoionization,
Kw = [H 30+][oH-], defines the relationship
between H 30+ and OH- concentrations in
aqueous solutions.
16.4 The pH Scale
We will use the pH scale (pH = -log[H+]) to
describe the acidity or basicity of an aqueous
solution. Neutral solutions have a pH = 7, acidic
solutions have pH below 7, and basic solutions
have pH above 7.
16.5
Strong Acids and Bases
We categorize acids and bases as being either
strong or weak electrolytes. Strong acids and bases
are strong electrolytes, ionizing or dissociating
completely in aqueous solution. Weak acids and
bases are weak electrolytes and therefore ionize
only partially.
16.6 Weak Acids
We learn that the ionization of a weak acid in
water is an equilibrium process with an
equilibrium constant Ka that can be used
to calculate the pH of a weak acid solution.
16.7 Weak Bases
We learn that the ionization of a weak base in
water is an equilibrium process with equilibrium
constant Kb that can be used to calculate the pH
of a weak base solution.
16.8
Relationship between Ka and Kb
We will see that a relationship exists between the
Ka and Kb of any conjugate acid-base pair:
Ka X Kb = Kw· Thus, the stronger an acid, the
weaker its conjugate base.
16.9
Acid-Base Properties of Salt Solutions
We will explore the fact that the ions of a soluble
ionic compound (a salt) can serve as
Bmnsted-Lowry acids or bases.
16.10 Acid-Base Behavior and Chemical Structure
We continue by exploring the relationship
between chemical structure and acid-base
behavior.
16.11 Lewis Acids and Bases
Finally, we learn the Lewis definitions of acid and
base. A Lewis acid is an electron-pair acceptor, and a
Lewis base is an electron-pair donor.
Citrus fruit, such
as the lemons shown in the chapter-opening photograph?
Sour cherries? Rhubarb? The sour taste of foods is due
primarily to the presence of acids. Citric acid (H3C6H 50 7),
malic acid (H2C4H40s), oxalic acid (H2C204), and ascorbic
WHAT IS THE SOUREST FOOD YOU'VE EVER TASTED?
acid, also known as vitamin C (HC 6H~ 6 ), are present in many fruits as well
as in certain vegetables, such as rhubarb and tomatoes.
Acids and bases are important in numerous chemical processes that occur
around us-from industrial processes to biological ones, from reactions in the
laboratory to those in our environment. The time required for a metal object
immersed in water to corrode, the ability of an aquatic environment to support fish and plant life, the fate of pollutants washed out of the air by rain, and
even the rates of reactions that maintain our lives all critically depend upon
the acidity or basicity of solutions. Indeed, an enormous amount of chemistry
·
can be understood in terms of acid-base reactions.
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