ch5 L3-solubility.pdf
Solubility
Chapter 5
Lesson 3
Objective
You will be able to
Define solubility, saturation and
equilibrium
Determine the factors that affect
solubility
Use the solubility chart to determine
which substances are soluble.
What factors affect how well a solute will dissolve in a
given solvent?
Nature of the solute and solvent
“Like Dissolves Like” - refers to the polarity of the
substances. Water is a polar molecule ie. Like a battery,
water has one end that is more negatively charged than
the other end. Substances that are polar, like water, will
dissolve in water. Substances that are nonpolar will not.
When making a Kool-Aid solution, you misread the
directions and put in two cups of sugar. You stir the
mixture for many minutes and yet the sugar does not
all dissolve, WHY? Discuss with a neighbor.
Solubility : THE CONCENTRATION OF A SATURATED SOLUTION
OF A SOLUTE IN A SOLVENT.
Saturated Solution : A SOLUTION THAT CONTAINS THE MAXIMUM
AMOUNT OF DISSOLVED SOLUTE AT SPECIFIED CONDITIONS.
Temperature
For solids - increase in temperature usually results in
an increase in solubility. Ex. more sugar dissolves in
hot water than in cold water.
For gases - reverse is true. The colder the solvent the
greater the solubility of gases. Ex. Soda pop and
carbon dioxide.
ch5 L3-solubility.pdf
Pressure
Very little effect on solids.
Gases - as pressure increases solubility increases.
Ex. Gases dissolve better under higher pressure such
as in pop cans.
Some solutions, or liquids, do not dissolve in water, but
form layers. Oil floating on water would be an
example. Such liquids are said to be immiscible with
water.
Other liquids dissolve in any and all proportions. That
is they have no maximum concentration. They are said
to be miscible with water.
How do we know which substances will be soluble?
Turn to page 6 of the data booklet.
Note: these apply to ionic solids only.
When a solution is saturated does the dissolving stop?
Discuss with a neighbor.
No! Molecules continue to dissolve into solution and
crystallize out of it. It is the rate of dissolving and
crystallization that remains the same. This is called
dynamic equilibrium. Note the directions of the
product arrows.
Assignment
Read p.176 - 183 in text.
Do #9,10,11