Molecular interactions, Physical property and IMF strength

Intermolecular interactions between chemical species can have more than one type of WHAT that can be present at the same time in a WHAT or WHAT species

Intermolecular interactions between chemical species can have more than one type of INTERMOLECULAR FORCES (IMFS) that can be present at the same time in a PURE or MIXTURE species

Intermolecular interactions between chemical species explaining WHAT

Intermolecular interactions between chemical species explaining PHYSICAL PROPERTIES

Interactions used to explain physical properties of WHAT or WHAT chemical species

Interactions used to explain physical properties of LIQUID or GASEOUS chemical species

Intermolecular forces and physical properties

• WHAT

• WHAT

• WHAT

• WHAT

• WHAT

Intermolecular forces and physical properties

• Miscibility

• Solubility

• Boiling point

• Viscosity

• Surface tension

The LESS the molecules are moving the WHAT the intermolecular forces (IMFs)

The LESS the molecules are moving the STRONGER the intermolecular forces (IMFs)

Miscibility

Ability of liquids to mix and form HOMOGENEOUS (i.e single phase, solutions)

Solubility

Ability of a solid solute to dissolve in a liquid solvent

General rule:

• One species will mix with another species if the interactions it has with the other species are WHAT or WHAT than the interactions it has with WHO

General rule:

• One species will mix with another species if the interactions it has with the other species are EQUAL or GREATER than the interactions it has with ITSELF

Boiling point

• WHAT at which a molecule leaves the liquid phase to enter the gas phase

• At that temperature enough WHAT provided to WHAT interactions between molecules in the liquid

• The stronger the interaction, the WHAT the boiling point

Boiling point

• TEMPERATURE at which a molecule leaves the liquid phase to enter the gas phase

• At that temperature enough ENERGY is provided to BREAK interactions between molecules in the liquid

• The stronger the interaction, the HIGHER the boiling point

Viscosity

• Ease of WHAT of species in the WHAT phase

• The stronger the interactions of the molecule with their neighbouring molecules, the WHAT distance it can travel and the WHAT the molecules move within the liquid

Viscosity

• Ease of MOVEMENT of species in the LIQUID phase

• The stronger the interactions of the molecule with their neighbouring molecules, the LESS distance it can travel and the SLOWER the molecules move within the liquid

Surface tension

The force that causes the molecules on the surface of a liquid to be pushed together and form a layer

example: The POLAR water molecules prefer to interact with the POLAR WATER molecules than the NON-POLAR molecules in the air *N2, O2, CO2)

Strength of intermolecular forces

• WHAT

• WHAT

• WHAT

• WHAT

• WHAT

Strength of intermolecular forces

• Shape

• Size

• Functional group

• Position of function groups

• Number of interactions

Shape

molecules with MORE branches: WHAT

molecules with MORE branches: LESS contact points for interactions

Size

LARGER molecules: WHAT

Size

LARGER molecules: MORE available contact points for interactions

Functional group: Order of decreasing IMF

1. Hydrogen bonding (Examples: C(O)OH, OH, NH, NH2,)

2. Dipole (example: any other groups that contain O, N)

• Dipole-dipole

• Dipole-induced dipole

3. LDF (Examples: C – C, C – H)

Position of function groups

A functional group located INSIDE a bulky molecular structure LESS accessible for interactions compared to the one at the END of a chain

Number of interactions

A LARGER number of weak IMFs can end up being STRONGER than a small number of STRONG IMFs.

In this case, the overall strongest IMF is the weak IMF and it will define the PHYSICAL PROPERTY of the molecules