Transcript Chapter 18 Notes I Solutions & Solubility Factors Affecting Solubility What is a Solution? • A solution is the same thing as a homogeneous.

Chapter 18 Notes I
Solutions & Solubility
Factors Affecting Solubility
What is a Solution?
• A solution is the same thing as
a homogeneous mixture (a
mixture with the exact same
composition throughout).
Parts of a Solution
• Solute-the substance that is
being dissolved in a solution
• Solvent-the substance in a
solution that is being dissolved
into.
Solution of Two Liquids
• When two liquids are able to dissolve
into each other, they are called
miscible.
• If not, they are called immiscible.
What can be dissolved?
• Remember the saying “like dissolves
like”
• Polar solvents (like water) will only
dissolve polar or ionic compounds.
*
How does solvation occur?
• IMFs between polar molecule pull ions
away from solid.
*
Solubility
• Solubility is the amount of a
substance that will dissolve into
a quantity of solvent (at a given
temperature)
Solubility Rules
• There are several sets of rules that can
help you to decide if a substance will be
soluble in water or not.
• More on this later!!!
Solubility, cont’d
• A solvent (like water, for
example) can only hold so
much of a solute.
• If a solvent cannot hold any
more of a solute (at that
temperature) it is called
saturated.
• If the solvent can hold more
solute, it is called unsaturated.
• Sometimes, a solution can hold
more of a solute than it should
theoretically hold. This type of
solution is called supersaturated.
• How could this occur?
Factors Affecting Solubility
• Generally, a substance’s solubility
increases as temperature is
increased. (This is not true of
most gases).
• Why? The solvent’s particles are
moving faster, and so they have
more energy to break bonds.
• In gases, pressure affects
solubility. The higher the pressure,
the more gas is soluble in a
solvent.
• What is an example of this?
Reading Solubility Charts
Concentration
• Concentration-the amount of solute
that is dissolved into a solvent
• Concentrated-when a solution has
a high concentration of solute
• Dilute-when a solution has a low
concentration of solute
Concentration…
• Concentration can be described
in terms of “weak” or “strong”,
“concentrated” or “dilute”, but
these are both relative terms
and can be subjective.
So how do we measure concentration
objectively? There are lots of ways!
Molarity
• Molarity is one way to measure
concentration; it is the number
of moles of solute per liter of
solution.
• The unit of molarity is mol/L,
which can be abbreviated with
an uppercase M.
Practice Problem #1
• What is the molarity of a
solution that contains 0.15mol
of MgCl2 in a 1.13L solution?
Practice Problem #2
• A saline solution contains
0.020mol of NaCl in exactly
100mL of water. What is the
molarity of this solution?
Practice Problem #3
• How many moles of solute are
present in a 1.5L sample of
0.24M Na2SO4?