Chapter 15 Forming Solutions
 Recall
a solution is a homogeneous
mixture of a solute and a solvent.
 The substance present in the largest
amount is the solvent.
 The solute solvent combination can be any
state: solid, liquid, or gas.
 If water is the solvent, it is referred to as
an aqueous solution.
The Dissolving Process
 When
an ionic substance dissolves water
separates the cation from the anion and
both become the solute in the solution.
 Soluble ionic compounds are more
attracted to the polar water molecule than
to the ionic complement in the crystal.
 Insoluble ionic compounds are more
attracted to each other than to the water
molecule.
The Dissolving Process
 Molecular
solutes dissolve in water if they
have similar bonding characteristics as
polar water.
 Ethanol, C2H5OH, dissolves in water
because the O-H bond is similar in polarity
to the O-H bond in water.
 “Likes dissolve like”
 Oil is a non-polar substance made with
non polar bonds between C and H so it is
NOT soluble in water.
“Dry” Cleaning
• Dry Cleaning uses a
non-polar solvent to
dissolve the dirt and
substances from your
clothes. Many fabrics
require this type of
solvent.
• Tetrachloroethylene
Cl2C=CCl2 is used for
the dry cleaning of
fabrics. It is non-polar
because the molecule
is symmetric and the
electrons are shared
more equally than in
water.
Concentration Terms
 Unsaturated

More solute can be put into the solution.
 Saturated

The maximum amount of solute is placed in
the solution.
 Supersaturated

More than the maximum amount of solute is
placed in the solution.
Saturation

A solution is said to be saturated when you
have the maximum amount of solute in the
solvent.
 At the point of saturation the solvent no
longer has the availability to break apart the
solute.
 If more solute is placed in the solution a state
of dynamic equilibrium is reached.
 The additional solute will dissolve, however
the dissolved solute will fall out of the solution
at the same rate.
Supersaturation






Changing the temperature of the solution will
affect the amount of solute allowed in the
solvent.
Increasing the temperature will increase the
solubility of endothermic dissolving processes.
Most solids are endothermic like this.
Decreasing the temperature will increase the
solubility of exothermic dissolving processes.
Most gases are exothermic like this.
A solution becomes supersaturated by
saturating it then lowering/raising the
temperature.
Vitamins
 Water
soluble (polar) vitamins like Vitamin
C are water soluble and can be taken daily
without concern. Your body excretes any
excess though the kidneys.
 Fat soluble (nonpolar) vitamins like
Vitamin A are fat soluble and are stored in
the tissue. It is possible to overdose on fat
soluble vitamins because your body has a
harder time removing the excess.
 Follow recommended amounts!
Homework
 Terms
Chapter 14
 Pg. 555 [4-11]