Chapter 23: Water and Solutions

Integrated Science
Unit 8, Chapter 23
Unit Eight: Water and the
Chapter 23 Water and Solutions
23.4 Acids,
Bases, and pH
Chapter 23 Learning Goals
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
hydrogen bond
nonpolar molecule
pH indicator
pH scale
polar molecule
solubility value
Tyndall effect
23.1 Water
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
 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
Water molecules behave
like a group of magnets.
The positive end of one
water molecule will align
with the negative end of
The formation of a bond
between the hydrogen on
one molecule to another
atom on another molecule
is called a hydrogen bond.
23.1 Water
Key Question:
What are the properties of
*Read text section 23.1
BEFORE Investigation 23.1
23.2 Solutions
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.
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
 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
The term solubility means the
amount of solute that can be
dissolved in a specific volume of
solvent under certain conditions.
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
*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
An acid is any substance that produces hydronium
ions (H3O+) when dissolved in water.
They react with metals to produce hydrogen gas (H2)
They change the color of a plant dye (called litmus)
from blue to red.
23.4 Acids, Bases, and pH
 Bases
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.