SOLUTION
INTERACTIONS AND
SOLUTION FORMATION
How do solvent and solute interact when
forming solutions?
Table of Contents
• Part 1: Critical Thinking Questions
• Parts of a solution
• More examples of solutions
• Intermolecular forces
• IMF in molecules and IMF in solutions
• Interactions in solutions
• How do IMF determine if a solution will form?
• Sugar/water and Oil/water
• Cleaning paint brushes
• Part 2: Solution Formation
• When the solute is covalent
• When the solute is ionic
• When the solute is an acid
PART ONE: CRITICAL
THINKING QUESTIONS
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Question 1
Parts of a Solution
Solvent
Solute
Solution
Solute
Solution
Solvent
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Question 1
More Examples of Solutions
Solute Solvent Solution
Examples
Gas
Gas
Gas
Air (O2 dissolved in N2)
Gas
Liquid
Liquid
Liquid
Liquid
Liquid
Solid
Liquid
Liquid
Liquid
Solid
Solid
Solid
Solid
Solid
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Carbonated soda (CO2 in water),
Swimming pool (Cl2 in water)
Wine (ethanol in water)
Vinegar (acetic acid in water)
Salt Water
Sugar Water
Dental amalgam for fillings (liquid
mercury in solid silver)
Alloys (14 karat gold: solid silver
and solid gold)
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Question 2
What are Intermolecular Forces?
Intramolecular forces:
Forces between atoms which
hold them together in molecules
(i.e. chemical bonds)
Intermolecular forces:
Attractive forces between
separate molecules, determines
properties like state of matter,
melting/ boiling point, volatility
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Question 3
What Kinds of IMF Exist between Molecules?
1. Dispersion
• Occurs between all covalent molecules
• Temporary changes in electron distribution
causes short lived polar attractions between
normally nonpolar molecules
2. Dipole-dipole
• Occurs between polar covalent molecules
• Positive pole of one molecule is attracted to the
negative pole of another molecule
3. Hydrogen bonding
• Occurs between molecules with H—F, H—O, or
H—N bonds only
• Partially positive hydrogen of one molecule is
attracted to the partially positive F, O, or N of
another molecule
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Question 4
What Kinds of IMF Exist in Solutions?
• Three kinds:
• Solute-solute (attractions between solute particles)
• Solvent-solvent (attractions between solvent particles)
• Solute-solvent (attractions between solute and solvent particles)
In order for a solution to form:
Solvent-solvent
and
Solute-solute
interactions
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<
Must be
weaker
than
Solute-solvent
interactions
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Question 5
Color Code Each Interaction
Solute-solute interactions
Solvent-solvent interactions
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Solute-solvent interactions
Now you
color in the
rest.
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Question 6
How do IMF Determine if a Solution will Form?
• Solutions form when the solute-solvent interactions overcome
the solvent-solvent and solute-solute interactions
• This only occurs when the solute and solvent are able to
interact very strongly with each other – this occurs when
solvent and solute have similar polarities.
Water has regions
of positive and
negative charge –
it’s polar!
This fatty acid (from
olive oil) is pretty
much all nonpolar.
Because water is polar and oil is nonpolar, they
cannot interact, and do not dissolve. Remember:
like dissolves like.
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Question 7
Sugar and Water
• Glucose is a polar covalent molecule, meaning each
glucose molecule has charges (which allow it to interact
with water and dissolve).
G
Glucose, a
sugar
molecule
Water, a
polar
solvent
Draw your solution
showing the solventsolvent, solute-solvent,
and solute-solute
interactions for sugar
water.
Remember, opposite
charges attract while
like charges repeal.
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Question 8
Oil and Water
• Oil is a nonpolar molecule while water is a polar molecule.
These different polarities mean that water and oil do not
interact enough to form a solution.
Oil
Oil
Oil
Oil
Oil, a
nonpolar
molecule
Water, a
polar
solvent
Draw your solution
showing the solventsolvent, solute-solvent,
and solute-solute
interactions for oil and
water.
Remember, oil and
water do not strongly
interact.
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Question 9
Cleaning Paint Brushes
Nonpolar
Polar
Compare the structure of turpentine to linseed oil.
• Are they polar or nonpolar?
• What types of elements are present?
Compare the structure of water to linseed oil.
• Are they polar or nonpolar?
• What types of elements are present?
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Which should you use
to clean the oil paint off
of the brushes, water or
turpentine?
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PART TWO: SOLUTION
FORMATION
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Question 10
When Polar Covalent Molecules Dissolve
+
+ -
G
-
G
+
G
+
G
G
G
G
G
-
G
G
G
Glucose is a polar
covalent molecule
with lots of positive
and negative
charges.
G
Glucose
(Sugar)
Cube
Glucose Molecule
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When many glucose
molecules are bonded
together, they for a
glucose crystal, such as
a sugar cube.
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Question 10
When Polar Covalent Molecules Dissolve
Click to add the
glucose to the
water.
This process is
simply referred
to as
dissolving.
G
G
G
G
G G
G
G
G
G
G
Notice that the sugar
is still a molecule –
the atoms didn’t break
Before
apart.
The water
molecules
surround the
glucose, based
on charge.
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G
G
G
G
G After
G
G
G
G
G
G
G
G
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Question 10
When Ionic Substances Dissociate
+1
-1
+1
-1
+1
-1
+1
-1
+1
Before Adding to Water
+1
Sodium
Cation
-1
Chloride
Anion
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Ionic substances, such
as NaCl, are made of
cations and anions.
They already
are made of
charges.
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Question 10
When Ionic Substances Dissociate
Click to add the
NaCl to the water.
+
+
+
-
After Adding to Water
+
+
Before Adding to Water
+
Once the salt is added, water
molecules begin colliding with
the salt crystal.
This process is called
dissociation, because the
charges in the ionic substance
already exist, they just need to
break apart (dissociate) from
each other.
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Once the ions break away
from the crystal, water
molecules surround them
based on charge.
+ - +
- + + - +
+ - +
- + + - +
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Question 10
When Acids Ionize
HCl is a polar molecule. The
chloride “pulls” much harder
on the shared electrons,
causing unequal sharing.
When added to water, the
water molecules will collide
with the HCl molecules,
causing the HCl atoms to
become fully charged
(ionized) as they form
solution.
δ+ H Cl δThis is due to the differing
electro negativities of the
atoms – Cl is more
electronegative than H.
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HCl has partial charges, it
does not have full charges.
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Question 10
When Acids Ionize
+
-
(HCl is a liquid)
Before Adding to Water
When water collides with the HCl, some
electrons are switched around, leading to
the formation of ions. This is called
ionization, because new ions are formed.
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After Adding to Water
+