Physical Science
Unit 6—Interactions of Matter
Chapter 22---Solutions
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Introductory Video 1
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22-1 How Solutions Form
Solution—a mixture that appears the
same throughout and is mixed at
the molecular level.
1.Solute --substance being dissolved.
2.Solvent –substance doing the
dissolving.
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3. Solutions can be liquids,
gases, or solids.
4. Alloys are solid
solutions.
Video—Alloys :31
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22-1 How Solutions Form
How dissolving happens:
1. Water molecules are polar—
they have a positive area and a
negative area.
Video—Polar Molecules :45
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2.Water molecules cluster around
solid molecules, with their
negative ends attracted to the
positive ends of the solids.
3.Water molecules pull the solid
particles into solution.
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22-1 How Solutions Form
4. The moving water molecules and solid
molecules spread out and mix evenly to
form a solution.
5. To mix solids to make an alloy
solution, you must melt the solid.
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22-1 How Solutions Form
Rate of dissolving depends on:
1. Stirring—speeds up dissolving by
bringing more fresh solvent into
contact with more solute.
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2. Crystal size
a. Dissolving occurs at the
surface of a solid
b. Breaking a solid into pieces
or powder increases its
surface area, which speeds
up dissolving.
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22-1 How Solutions Form
To make a gas dissolve more
quickly in a liquid, cool the liquid
solvent and increase the pressure
of the gas.
Video Temp., pressure, Other Factors 1.59
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22-2 Dissolving Without Water
Non-polar materials have no positive
or negative area.
1.They are not attracted to the polar
water molecules, so they do not
dissolve easily in water.
Video Non-Polar Molecules 1.49
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1. Example: oils contain
hydrocarbons.
a.Large molecules of carbon and
hydrogen
b. These atoms share electrons in an
equal manner, so there is not
positive or negative charge.
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22-2 Dissolving Without Water
Useful non-polar molecules
1.Non-polar solvents dissolve non-polar
solutes.
2. Many non-polar solvents are toxic—
dangerous to touch or inhale.
3. Soap—used for washing because it has
polar and non-polar properties.
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22-2 Dissolving Without Water
Polarity and Vitamins
1. B vitamins and vitamin C are polar—
dissolve in the water in your body cells.
2. Vitamin A is non-polar –dissolves in the
fat of some body cells.
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22-3
Solubility and Concentration
Solubility—the amount of a substance that
can dissolve in a solvent
1.Depends on the nature of the substance
2. The solubility of two substances can be
compared by measuring.
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22-3
Solubility and Concentration
Concentration-1. A concentrated solution
has a large amount of
solute in the solvent
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22-3
Solubility and Concentration
2. A dilute solution has a small
amount of solute in the
solvent.
3. Concentrations can be
expressed as percent by
volume of the solute.
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22-3
Solubility and Concentration
Types of solutions.
1.Saturated solutions —
contains all the solute it can
hold at a given temperature.
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22-3
Solubility and Concentration
a.As the temperature of a liquid
solvent increases, the amount of
solid solute that can dissolve in it
increases.
b. Solubility curve—line on a
graph used to figure how much
solute can dissolve at any
temperature on the graph.
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22-3
Solubility and Concentration
2.Unsaturated solution —able to
dissolve more solute at a given
temperature.
3. Supersaturated solution —
contains more solute than a
saturated one at the same
temperature
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Super-saturated solution is
made by raising temperature
of a saturated solution,
adding more solute, and
lowering temperature back
without disturbing the
solution.
Video-Saturated-Supersaturated 1:22
Video-Temperature, etc. 1:59
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b. Unstable– will crystallize
if disturbed.
c. As it crystallizes, it gives
off energy and produces
heat.
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22-4
Particles in Solution
Ions —particles with a charge
1.Electrolytes—compounds that form
charged particles (ions) and conduct
electricity in water.
2. Non-electrolytes—substances that do
not ionize in water and cannot
conduct electricity
Video—Ions 1.48
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22-4
Particles in Solution
How ions form
1.Ionization –molecules break apart in
water, causing atoms to become ions
by taking on a charge.
2. Dissociation —an ionic solid
separates into its positive and negative
ions.
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22-4
Particles in Solution
Effects of solute particles
1.All solute particles—polar,
non-polar, electrolyte, and
non-electrolyte—affect the
physical properties of the
solvent.
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Adding a solute to a solvent lowers
the freezing point because the
added solute particles interfere
with the formation of the orderly
freezing pattern.
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Adding a solute raises the
boiling point because fewer
solvent molecules can
reach the surface and
evaporate.
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Review for the Test over
Chapter 22
All Homework will be due _______.
REVIEW
Will increasing the temperature
increase the solubility of a
solute in a solvent?
Sometimes, but not always
REVIEW
Will the type of solution
depend on the state of the
solute?
No
REVIEW
Are the particles of a a liquid
moving?
Yes, constantly.
REVIEW
When water dissolves sugar, are the
positive ends of the water molecules
attracted to the negative ends of the
sugar molecules?
No.
REVIEW
Which particles move more
freely: solid, liquid or gas?
Gas. Solids move less freely.
REVIEW
True or false: The dissolving
process for solid solutions
occurs in the solid state.
False
REVIEW
Will salad oil dissolve in
vinegar?
No
REVIEW
Oil-based paints, nail polish
and iodine are examples of
_______ solutions.
Non-polar
REVIEW
Water can be used to dissolve
_______ molecules.
polar
REVIEW
Explain why Vitamin C is
polar.
Vitamin C has several oxygen-tohydrogen bonds resembling
those found in water.
REVIEW
Does a non-polar material have
separated positive and
negative areas?
No
REVIEW
Describe the sharing of
electrons by hydrogen and
carbons in hydrocarbons.
They share electrons nearly
equally.
REVIEW
Explain how to express the
concentration of a solution to
solute.
Express in terms of percentage
by volume of the solute.
REVIEW
If a drink has 10% fruit juice
does this mean that it is 100%
by volume of the drink?
No, it is only 1/10 fruit juice.
REVIEW
What is a solute?
The substance being dissolved.
REVIEW
A _______ does not conduct an
electric current when it forms
a solution.
A non-electrolyte.
REVIEW
A soltion that contains all of
the solute it can hold at a
given temperature is ____.
Saturated
REVIEW
The process by which the positive
and negative ions of a crystalline
solid separate in water is called
_______.
dissociation
REVIEW
Increasing the surface area of a
solid will ____ the rate of
solution.
speed
REVIEW
When a gas is dissolved in a
liquid, the gas dissolves faster
if the liquid is _____.
Cooled.
REVIEW
The concentration of a solution
that contains a large amount of
solute in the solvent could be
described as ____.
concentrated
REVIEW
An alloy is an example of a
____ solution.
solid
REVIEW
Adding more solute to a solvent
increases its ______.
Boiling point
REVIEW
A molecule that is positively
charged on one end and
negatively charged on the other
end is ____.
Polar.
REVIEW
The amount of solute that can be
dissolved in a specific amount of
solvent at a given temperature is
its ______.
solubility.
REVIEW
If we increase the pressure and
decrease the temperature we
would ____ the solubility of a
gas in a liquid.
increase
REVIEW
Stirring the solution will ____
the speed of dissolving of the
solid in water.
increase