Integrated Science
Unit 8, Chapter 23
Unit Eight: Water and the
Environment
Chapter 23 Water and Solutions
23.1
Water
23.2
Solutions
23.3
Solubility
23.4 Acids,
Bases, and pH
Chapter 23 Learning Goals
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Identify and describe the unique properties of water.
Describe the shape and polarity of a water molecule.
Discuss the nature of hydrogen bonds and their influence on the
properties of water.
Identify the components of a solution.
Categorize mixtures as solutions, suspensions, or colloids.
Define solubility.
Describe saturated, unsaturated, and supersaturated solutions.
Explain how temperature and pressure influence solubility.
Understand solubility values.
Interpret temperature-solubility graphs.
Identify the characteristic properties of acids and bases.
Relate the pH scale to examples of acids and bases.
Chapter 23 Vocabulary Terms
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acid
alloy
base
colloid
dissociation
dissolved
electrolyte
equilibrium
hydrogen bond
nanometer
neutralization
nonpolar molecule
pH
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pH indicator
pH scale
polar molecule
saturated
solubility
solubility value
solute
solution
solvent
suspension
supersaturated
Tyndall effect
unsaturated
23.1 Water
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A water molecule is made
of one oxygen atom that
forms a chemical bond with
two hydrogen atoms.
 Because
negative charges
repel, the four electrons
pairs around the oxygen
atom are located where
they can be the farthest
apart from each other.
23.1 Water
 The
geometric shape that
allows them to be the
farthest apart is called a
tetrahedron.
 In
a molecule of water, the
electrons are shared
unequally between oxygen
and hydrogen.
23.1 Water
 Water
is a polar molecule that
is, it has a negative end (pole)
and a positive end (pole).
 The
oxygen side of the
molecule has a partially
negative charge and the
hydrogen side of the molecule
has a partially positive charge.
23.1 Hydrogen Bonding and Water
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Water molecules behave
like a group of magnets.
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The positive end of one
water molecule will align
with the negative end of
another.
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The formation of a bond
between the hydrogen on
one molecule to another
atom on another molecule
is called a hydrogen bond.
hydrogen
bonds
23.1 Water
Key Question:
What are the properties of
water?
*Read text section 23.1
BEFORE Investigation 23.1
23.2 Solutions
A
solution is a mixture of two or more
substances that is homogeneous at the
molecular level.
 The
particles in a solution exist as individual
atoms, ions, or molecules.
A
solution is a mixture of
solute dissolved in a solvent.
 (An
alloy is a solution of two
or more metals.)
Solutions, Solutes and Solvents
23.2 Colloids and Suspensions
 Colloids
and suspensions are not solutions.
23.2 Colloids and Suspensions
 Colloid
particles are formed from clusters of
atoms or molecules.
 Suspensions
are mixtures that settle upon
standing.
 Filtering
a suspension will separate the
different components.
23.2 Solutions
Key Question:
Can you identify mixtures as solutions,
suspensions, or colloids?
*Read text section 23.2
BEFORE Investigation 23.2
23.2 Solution Concentrations
 Molarity
is one way of expressing the
concentration of a solution.
Molarity (M) = Moles of solute
Liters of solution
23.2 Solution Concentrations
 Mass
percent is another way to express
concentration of solutions.
Mass percent = mass of solute x 100%
tot. mass of solution
23.3 Solubility
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The term solubility means the
amount of solute that can be
dissolved in a specific volume of
solvent under certain conditions.
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Several factors affect solubility:
— chemical nature of the solvent
— the volume of solute
— temperature
23.3 Solubility of Gases
 The
solubility of gases in
liquids decreases as
temperature increases.
 The
solubility of a gas also
depends on pressure.
23.3 Solubility
Key Question:
What factors affect
solubility?
*Read text section 23.3
BEFORE Investigation 23.3
23.4 Acids, Bases, and pH
Key Question:
What is pH?
*Read text section 23.4
AFTER Investigation 23.4
23.4 Acids, Bases, and pH
 Acids
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An acid is any substance that produces hydronium
ions (H3O+) when dissolved in water.
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They react with metals to produce hydrogen gas (H2)
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They change the color of a plant dye (called litmus)
from blue to red.
23.4 Acids, Bases, and pH
 Bases
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A base is any substance that produces hydroxide ions
(OH-) when dissolved in water.
 While you should never touch a laboratory chemical,
the bases you use every day such as soap, have a
slippery feel.
 They change the color of litmus from red to blue.
23.4 Acids and bases in your body
 It
is very important for your
blood pH to stay within the
normal range.
 The
rate at which you
breathe controls the
concentration of carbon
dioxide in your blood.