Topic 6 : organic chem

• What is the molecular formula?


  the number and type of each atom in a molecule
• What is the empirical formula?


  the simplest whole number ratio of the elements present in one molecule of the compound
• What is nomenclature?


  Naming system for compounds
• What is the displayed formula?


  Shows every atom and every bond in a molecule
• What is the structural formula?


  Shows arrangement of atoms in a molecule without showing every bond
• Define homologus series


  Series of organic compounds having the same functional group, each differing by CH2
• What is a functional group?


  A group of atoms responsible for characteristic reactions of a compound
• Define structural isomerism


  same molecular formula different structural formula
• What are the 3 ways structural isomers can be formed?

  .Alkyl groups can be in different places

  .functional groups bonded to different places

  .different functional groups
• What are stereoisomers?

  Stereoisomers are molecules that have the same molecular formula, but differ in the arrangement of atoms in space.
• What is E-Z isomerism?

  How are they different?

  .Caused by the limited rotation about C=C double bonds

  .z isomer= same side

  .e isomer= different side
• What is cis/trans isomerism?


  Special type of E/Z isomerism where the two substituents on each carbon atom are the same

  Can only be used when there are hydrogen atoms to compare the other groups to
• What does saturated mean?

  Organic compounds that only contain single bonds
• What does unsaturated mean?

  Organic compounds that contain at least one carbon-carbon double bond
• What is homolytic fission?

  When each bonding atom receives one electron from the bonding pair, forming 2 radicals
• What is heterolytic fission?

  When one bonding atom receives both electrons from the bonded pair
• What are radicals?

  Highly reactive, neutral species

  An atom/molecule/ion that has at least one unpaired valence electron
• What is the general formula for alkanes?

  CnH2n+2.
• What is the general formula for alkenes?

  CnH2n.
• How is a covalent bond formed from two radicals?

  The radicals collide and the electrons are formed in the bond formation
• How are alkane fuels obtained?

  Fractional distillation

  Cracking

  Reformation of crude oil
• Describe the process of fractional distillation of crude oil

  • Oil is pre-heated and passed into a column
  • Fractions condense at different heights and the temperature of the column decreases upwards
  • Separation of the fuels depends on the boiling point which depends on the size of the molecule (larger the molecule, larger the London forces)
  • Similar molecules (size,bp,mass) condense together so are collected at the same fraction
  • Small molecules condense at the top at lower temperatures, bigger molecules condense at the bottom at higher temperatures
• What is cracking?

  . Converting large hydrocarbons to smaller molecules by breakage of C-C bonds
• What is the reforming of crude oil?

  Processing of straight chain hydrocarbons into branched chain alkanes and cyclic hydrocarbons for efficient combustion
• What are the two types of cracking?

  Thermal- High temps and pressures (1200K, 7000kPa) used to crack carbon chains. Always forms an alkane and atleast one alkene

  Catalytic- zeolite catalyst used, lower temperature(720K), produces aromatic compounds
• What is the shape and angle of an alkane?

  Shape: Tetrahedral Angle: 109.5 degrees
• Describe the sigma bons in an alkane

  Covalent bond that has a direct overlap of electron clouds of the bonding atoms
• How reactive are alkanes?Why?

  Very unreactive

  They are non-polar molecules and have strong bonds
• What reactions will alkanes undergo?

  Combustion, halogenation, and cracking.
• What type of reaction is combustion?

  Oxidation
• What is complete combustion?

  Combustion with sufficient oxygen present, produces carbon dioxide and water
• What is the colour of the bunsen burner flame during complete combustion?

  Blue
• What is incomplete combustion of alkanes and what products are formed?

  Incomplete combustion:

  - insufficient oxygen is present Carbon monoxide, carbon (soot), water.
• What type of hydrocarbons are most likely to undergo incomplete combustion?

  Longer chains
• What are the pollutants formed during the combustion of alkanes?

  carbon monoxide, nitrogen oxides, sulfur oxides, carbon particulates and unburned hydrocarbons
• What is the environmental impact of carbon monoxide?

  It is toxic/ poisonous
• What is the environmental impact of soot (carbon)?

  • Asthma
  • Cancer
  • Global warming
• What are the environmental impacts of nitrogen oxides?

  • NO is toxic and can form smog
  • NO2 is toxic, acidic and forms acid rain
• What are the environmental impacts of unbranched hydrocarbons?

  Contribute towards the formation of smog
• What is the importance of a catalytic converter?

  They remove CO, nitrogen and unburned hydrocarbons ( e.g octane) from the exhaust gases, turning them into less toxic products (CO2, N2, H2O)