Chapter 3.
8-E. Science
Working with solutions.
 Suspension:
mixtures in which particles
can be seen and easily separated.
 Solution: a well mixed mixture.
Solvents and solutes.
 Solvent:
the part of a solution, present and
largest amount.
 Solute: a substance that is present in a
smaller dissolved by the solvent.
 Water is the universal solvent.
 Many solutions can be made from gases
or solids.
Particles in a solution.
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Whenever a solution forms, particles of the
solute leave each other and become
surrounded by particles of the solvent.
Ionic solids and water- water molecules
surround each ion as it leaves the surface of a
crystal.
Molecular solids and water- molecular solids
break into individual neutral molecules.
Solutions & conductivity- if ions are present it’s
ionic and conducts electricity, otherwise it’s
covalent and does NOT conduct electricity.
Concentration.
 Dilute
Solutions- when only a little solute
dissolves in water.
 Concentrated Solution- it has more solute,
dissolves in water.
Solubility.
A
measure of how much a solute can
dissolve in a solvent in a given
temperature.
 Saturated solution- when you’ve added
so much solute that no more dissolves.
 Unsaturated Solution- where you can
dissolve more solute.

Changing Solubility.
 The
factors that effect the solubility of a
substance include: temperature, and
type of solvent.
 Temperature- increase add more solute.
 Solvents: like substances dissolve. (ionic
dissolves ionic, covalent dissolves
covalent.)
Effects of solutes on solutions.
Solutes lower the freezing point, and raise
the boiling point.
Describing Acids and Bases.
 Properties
of Acid include: sour taste,
reacts with metals and carbonates, and
changes blue litmus changes red.
 Corrosive- eat way at other materials.
 Indicators- a compound that changes
color, in the presence of a acid or base.
Properties of bases.
 The
properties of bases include: bitter
taste, slippery feeling, & reaction with
indicators.

Acids and bases in solution.
 Hydrogen
ion: an atom of hydrogen that
has lost its electron.
 Positive charge
 An acid is any substance that forms a
hydrogen ion in water.
 Hydroxide ion: polyatomic made of
oxygen and hydrogen ( O H -)
 A base is any substance that forms any
hydroxide substance in water.
Strengths of acids and bases
 pH
scale-a series of numbers from zero to
14.
 Measures the concentration of hydrogen
ions in a solution.
 When the pH is low the concentration of
hydrogen ions is high.
 when the pH is high the concentration of
hydrogen ions is low.
Acid rain
 Normal
rain has a pH of approximately
5.5, acid rain has a pH between 3 to 3.5.
 Acid base reactions- when you mix an
acid and a base you get a salt or a
neutralized mixture with a pH of 7.
 A neutralized reaction produces water
and salt.
Digestion and pH
 Digestion-
the breaking down of foods
into simpler substances that the body can
use for raw materials and energy.
 Mechanical digestion- Tears, grinds and
mashes large food particles into smaller
ones.
 Chemical digestion- Breaks larger
molecules into smaller molecules using
enzymes and acids.
pH in the digestion system
 For
some digestive enzymes the pH must
be low, and for others it must be high or
neutral.
 Mouth- Enzyme amylase, pH is neutral.
 Stomach- Hydrochloric acid and pepsin,
pH is acidic.
 Small intestine- pH level is 8/basic.