Le Chatelier's Principle and Carbon Chemistry Properties

Le Chatelier's Principle

Changes in Concentration

When a quantity of a substance is added to an equilibrium system, it will move to the side where the substance is not present. If, however, we remove one of the substances, the equilibrium shifts to the side where it is located.

Changes in Pressure Affecting Volume

When the pressure is increased from the outside and the system decreases in volume, the equilibrium shifts in the direction where there is a smaller number of moles (or molecules) to counteract the external perturbation.

Changes in Temperature

An increase in temperature always favors the endothermic process, and a decrease favors the exothermic process. If the direct process is endothermic, a temperature increase leads to a higher value of Kc, and if it is exothermic, a decrease.

Effect of a Catalyst

The addition of a catalyst to a process in equilibrium does not change its state.

Carbon Chemistry Properties

Alkanes

• Are nonpolar molecular substances.
• The molecules are linked by van der Waals dispersion forces (which increase with molecular size).
• Due to their nonpolar nature:
  • Insoluble in water.
  • Very soluble in nonpolar solvents.
• Very low melting and boiling points.

Alkenes and Alkynes

• Have nonpolar covalent bonds.
• Van der Waals dispersion forces.
• Insoluble in H2O and soluble in nonpolar solvents.
• Lower melting and boiling points.

Aromatic Hydrocarbons

• Flat structure.
• Relatively high melting and boiling points.
• Insoluble in water and soluble in organic solvents.

Alcohols

• Polar molecules.
• Molecules united by hydrogen bonds.
• Increasing melting and boiling points.
• Water-soluble, reducing this solubility with increasing carbon number.

Ethers

• Lower melting and boiling points.
• Water-soluble.
• Dissolve organic substances.

Aldehydes and Ketones

• High dipole moment of the molecule, very strong intermolecular forces.
• Melting and boiling points higher than hydrocarbons and lower than alcohols.
• Water-soluble.
• Very soluble in organic solvents.

Acids and Esters

• Are linked by hydrogen bonds.
• Esters are less soluble in water than acids, with lower melting and boiling points.

Amines

• The molecules are linked by hydrogen bonds.
• Boiling point and solubility in H2O are lower than alcohols.

Amides

• Very strong intermolecular forces.
• Solid substances.
• Less basic than amines.

Nitro and Nitrile Compounds

• Water-soluble.
• Higher melting and boiling points.