Intermolecular Forces and Solubility

  Solution is a homogeneous mixture of two or more substance

  Solute is (are) the substance(s) present in small amount(s)

  Solvent is the substance present in larger amount

  Solubility of a solute is the maximum amount that dissolves in a fixed quantity of a particular solvent at a specified temperature.

  Dilute contains less amount of solute than concentrated solutions

  Concentrated contains more amount of the solute than dilute solutions

  Dilute and Concentrated are relative and qualitative terms

IMFs in Solution

IMFs in Solution

  Aqueous Salt Solutions: NaCl (solute) in Water (solvent)  Water H-bonds  NaCl ionic bonds   Ion-dipole forces

  Hydration Shells

Like Dissolves Like

When a solute dissolves in a solvent, solute-solute interactions and solvent-solvent interactions are partly replaced with solute-solvent interactions.

The new forces created between solute and solvent must be comparable in strength to the forces

destroyed within the solute and within the solvent

Like Dissolves Like

  non-polar molecules are soluble in non-polar solvents

  CCl4 in C6H8 (hexane)

  polar molecules are soluble in polar solvents

  C2H5OH in H2O

  ionic compounds are more soluble in polar solvents

  NaCl in H2O or NH3 (l)

Exercises

Which of the following pairs is likely to be more soluble in water?

a)  CH3CH2CH2CH2OH or CH3CH2OH b)  CCl4 or CaCl2

c)  C6H6 or C6H5OH

IMFS AT WORK

The Cleansing Action of Soap

  Crude oil contains many different kinds of oils and organic compounds. Why is it possible to separate these oils via fractional distillation?  Why is methane gas at room temp?  Why is motor fuel liquid?  Why is asphalt solid?

  ALL OF THESE COMPOUNDS ARE PREDOMINANTLY HYDROCARBONS…

A barrel of oil…

Refinery Gases (Petroleum gases)

C1- C4 Simple chain alkanes

(chemicals industry feedstock, gases…fuel)

Gasoline (light naphtha)

C5- C6 Linear chain molecules

branched-chain molecules (motor fuel - gasoline)

Naphtha for Chemicals (heavy naphtha)

C6-C10

Straight-chain and branched alkanes, aromatics and

naphthenes (chemical industry feedstock)

Kerosene (paraffin)

Complex/ higher alkanes, aromatics and naphthenes (Aviation fuel)

Gasoil (Diesel) C14-C19

Lubricating oil, Waxes

Over C35

Long straight-chain alkanes, branched- chain alkanes, complex naphthenes

and aromatics, mixed types

C10-C14

Complex alkanes, aromatics and naphthenes, mixed types (alkane-

naphthene aromatics (heavy duty fuel diesel)

Asphaltenes and resins, long-chain alkanes: including waxes, naphthenes, aromatics,

branched-chain alkanes, mixed types

C19-C35

Bitumen

Distillation

40 C o

40-110 C o

110-180 C o

180-230 C o

230-425 C o

425+ C o

Heater

Crude Oil

Fractionating columns

Proteins

  Poly-amino acid chains

  Folding/Structure dictates function

  Like dissolves like still applies

Proteins

Proteins

Deoxy Ribonucleic Acid

Deoxy Ribonucleic Acid

Sugars

Glucose: Energy or Strength

Glucose: Energy or Strength

Lipids

cholesterol

The Cell Membrane

Lauric Acid and Monolaurin

  Lauric acid is a 12-carbon fatty acid