org mol lec

• Alkanes


  Open-chain aliphatic hydrocarbons with the type formula CnH2N
• Alkanes


  • Saturated compounds
  • Lowest boiling point
• Structural isomers


  Compounds with the same molecular formulas but different structures
• Saturated compounds


  • Characterized by the presence of only single bonds in the molecules
• Cycloalkanes


  Saturated hydrocarbons containing rings of carbon atoms
• Cycloalkanes


  • Ring size from three to thirty are found in nature
  • CnH2n
  • Three-dimensional shapes
• Increase in molar mass, carbon, and less branching


  Increases boiling point of alkanes
• Alkanes


  • Burn in air or pure oxygen to form carbon dioxide, and water
  • React with halogens
  • Do not react with aqueous solutions of acids, bases and mild oxidizing agents like potassium permanganate
• Methane


  • Burns with a pale blue flame, giving carbon dioxide and water
  • Reacts with bromine faster in light
  • Will not decolorize an alkaline solution of potassium permanganate, being a saturated hydrocarbon
• Methane + bromine


  Hydrogen bromide
• Thermal decomposition


  Large molecular weight alkanes are broken down into smaller ones by heat. This process is employed in the refining of petroleum
• Alkanes


  • Do not dissolve in polar solvents like water
  • Dissolve in nonpolar solvents like ether and chloroform
  • Therefore they are non-polar
• Alkanes


  • Density increases with size but tends to level off at 0.8 g/ml
  • Less dense than water, hence they float on water
• Combustion


  The reaction with oxygen to form carbon dioxide, water, and most important of all – heat
• Uses of alkanes


  • Cooking - kerosene for kerosene stoves, biogas or LPG (liquefied petroleum gas) for gas stove
  • Lighting - candles, kerosene for lamps, and LPG in novelty lighting fixtures during brown-outs
  • Farming/fishing - diesel to run tractors, motorboats, and simple farm machines
  • Transportation - gasoline or diesel to run buses, cars, jeepney, tricycle
  • Generation of electricity - kerosene for small generators, bunker fuel for big power plants
• Alkane categories by carbon number


  • C1 to C4 - Gas alkanes
  • C5 TO C16 - Liquid alkanes
  • Above C16 - Solid alkanes
• Solvents where alkanes are soluble


  • Ether, benzene, organic liquids
• Polymerization


  Gaseous alkanes are commonly used as fuels, in the production of gasoline
• Uses of liquid alkanes


  • Used as solvent, motor, fuel, and illuminating fuel
• Uses of solid alkanes (paraffins)


  • Used in the manufacture of candles, in home canning, and in waterproofing fabrics