org chem

• what is a homologous series ?

  a grp of compounds with a general formula similar chemical properties and show a gradation in physical properties as a result of an increase in the size and mass of the molecules
• genral formula of

  • alkanes
  • alkenes
  • alcohols
  • carboxylic acids 


  CnH2n+2

  CnH2n

  CnH2n+1OH

  CnH2n+1COOH
• prefix 


  meth

  eth

  prop

  but

  pent

  hex
• r/s of physical properties from one member to the next member

  the melting and boiling point increases

  they become more flammable

  they become more viscous
• what is unsaturated ?

  means they contain carbon carbon double bonds
• combustion reaction products 


  CO2(g) and H2O(g)
• addition of hydrogen (hydrogenation)

  conditions, application

  200* nickel catalyst

  margarine from vegetable oil
• additong of steam(hydration)

  conditions

  applications

  300*, 60atm, phosporic(V) acid catalyst

  change alkene to alcohol
• addition polymerization

  conditions

  applications

  high temperatue and pressure and presence of catalyst

  to make plastic bags
• cracking

  conditions

  importance

  600* Aluminum oxide and silicon dioxide as catalyst

  long chain into short chain

  to produce hydrogen

  to produce short chain alkenes
• fermentation

  condition

  glucose mixed with yeast

  37* water and yeast as catalyst (absence of air)
• why must fermentaion be at absence of air?

  presence of air, bacteria from the air oxidises ethanol to ethanoic acid
• why 37* for fermentation

  enzymes work best(body temp) if temp is raised beyond that, enzymes will denature and be unable to catalyse rhe reaction fermentation will stop
• chemical test to differentiate between saturated(single bonds) and unsaturated(double bonds)

  use aq bromine, double bond turn reddish brown aq bromine colourless, no visible reaction for single bond.