Solution Interactions and Solution Formation

SOLUTION INTERACTIONS AND SOLUTION FORMATIONHow 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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Parts of a Solution

Solvent

SolventSolute

Solute Solution

Solution

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Question 1

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More Examples of SolutionsSolute Solvent Solution ExamplesGas Gas Gas Air (O2 dissolved in N2)Gas Liquid Liquid Carbonated soda (CO2 in water),

Swimming pool (Cl2 in water)Liquid Liquid Liquid Wine (ethanol in water)

Vinegar (acetic acid in water)Solid Liquid Liquid Salt Water

Sugar WaterLiquid Solid Solid Dental amalgam for fillings (liquid

mercury in solid silver)Solid Solid Solid Alloys (14 karat gold: solid silver

and solid gold)

Question 1

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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

Question 2

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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

Question 3

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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-solventand

Solute-soluteinteractions

Solute-solvent interactions<

Must be weaker

than

Question 4

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Color Code Each Interaction

Solute-solute interactions

Solvent-solvent interactions

Solute-solvent interactions

Now you color in the

rest.

Question 5

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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.

Question 6

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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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 OH H

Draw your solution showing the solvent-

solvent, solute-solvent, and solute-solute

interactions for sugar water.

Remember, opposite charges attract while like charges repeal.

Glucose, a sugar

molecule

Water, a polar

solvent

Question 7

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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.

OH H

Draw your solution showing the solvent-

solvent, solute-solvent, and solute-solute

interactions for oil and water.

Remember, oil and water do not strongly

interact.

Oil, a nonpolar molecule

Water, a polar

solvent

Oil Oil Oil Oil

Question 8

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PART TWO: SOLUTION FORMATION

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When Polar Covalent Molecules Dissolve

G

+

+ -++ -

-

-

Glucose is a polar covalent molecule with lots of positive

and negative charges.

G Glucose Molecule

G

GG

GG

GG

G

G

G

Glucose (Sugar)Cube

When many glucose molecules are bonded

together, they for a glucose crystal, such as

a sugar cube.

Question 9

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When Polar Covalent Molecules DissolveClick to add the glucose to the

water.

Before

GGG

GG

G

GG

G

G

GG

GG

GG

G

GG

G

G

G

GGG

GG

G

GG

G

G

GAfter

The water molecules

surround the glucose, based

on charge.

This process is simply referred

to as dissolving.

G

G

Notice that the sugar is still a molecule –

the atoms didn’t break apart.

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Question 9

When Ionic Substances Dissociate

+1 -1 +1

-1 +1 -1

+1 -1 +1

+1

-1

Sodium Cation

Chloride Anion

Ionic substances, such as NaCl, are made of cations and anions.

They already are made of

charges.Before Adding to Water

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Question 9

When Ionic Substances Dissociate

+ - +- + -+ - +

Click to add the NaCl to the water.

+ - +- + -+ - +

+ - +- + -+ - +

+ - +- + -+ - +

Once the salt is added, water molecules begin colliding with

the salt crystal.

Once the ions break away from the crystal, water

molecules surround them based on charge.

-+

This process is called dissociation, because the

charges in the ionic substance already exist, they just need to break apart (dissociate) from

each other.

After Adding to Water

Before Adding to Water

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Question 9

When Acids Ionize

H Clδ+ δ-

HCl is a polar molecule. The chloride “pulls” much harder

on the shared electrons, causing unequal sharing.

This is due to the differing electro negativities of the

atoms – Cl is more electronegative than H.

HCl has partial charges, it does not have full charges.

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.

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Question 9

When Acids Ionize

HCl

H Cl

Before Adding to Water After Adding to Water(HCl is a liquid)

+ -

- +

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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Question 9