Organic Chem (Topic 7)

• Crude oil is a FINITE resource, meaning it will eventually run out.
• Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud.
• What is crude oil made from?

  Many compounds, mainly hydrocarbons
• What is a hydrocarbon?

  A molecule which only contains hydrogen and carbon atoms
• What are most of the hydrocarbons in crude oil?

  Alkanes
• What is the general formula for alkanes?

  The general formula for alkanes is CnH2n+2.
• What are the first 4 alkanes?

  Methane (CH4), Ethane(C2H6), Propane (C3H8), Butane (C4H10)
• How is crude oil separated?

  Fractional distillation
• In fractional distillation, how are hydrocarbons separated?

  By the amount of carbon atoms
• Different fractions have different boiling/melting points, this causes them to condense at different temps so it seperated

  
• What other substances are produced by the petrochemical industry?

  • solvents,
  • lubricants,
  • polymers,
  • detergents,
• Why are alkanes saturated compounds?


  they contain only single covalent bonds.
• What is a homologous series?

  A homologous series is a group of organic compounds that have the same functional group and follow a similar structural pattern/properties
• What is the functional group of alkanes?

  C-C , single carbon-carbon bond
• As the length of hydrocarbon increases (ALKANE) how does this affect the boiling point?

  As length increases, boiling points increases as more bonds needed to break so more energy required
• Why are alkanes less reactive than alkenes?

  Alkanes are saturated hydrocarbons, strong C-C and H-H bonds,
• How does the viscosity (runniness) of the hydrocarbons change as the length increases?

  Viscosity increases, CH4 (low viscosity)-> C4H10 (high viscosity)
• How does flammability change as the length of hydrocarbons increases?

  Flammability decreases, CH4 (high flammable), C4H10 (low flammability)
• What is the complete combustion of a hydrocarbon?

  Hydrocarbon + oxygen - Carbon dioxide +Water
• When does complete combustion occur?

  When there is a sufficient supply of oxygen
• What is the equation for incomplete combustion?

  hydrocarbon + oxygen (not enough) -> carbon monoxide CO + water H20
• How are hydrocarbons broken/seperated?

  Cracking
• What are the 2 forms of cracking?

  • catalytic
  • Steam cracking
• What does the cracking of alkanes produce?

  Alkenes
• What is used to test for alkenes?

  Bromine water (orange/red - colourless)
• Are alkanes or alkenes more reactive?

  Alkenes, unsaturated, new bonds formed quicker causing higher reactivity
• Why is cracking alkanes useful?

  Creates smaller molecules (alkenes) which are used for high demand fuels
• What are alkenes used for?

  Polymers
• What is the general formula for alkenes?

  CnH2n (double C=C bonds - functional group)
• Why are alkenes unsaturated?

  Contain 2 fewer hydrogen atoms than alkanes, double c=c bonds
• What are the first 4 alkenes?

  • ethene,
  • propene,
  • butene,
  • pentene,
• What is catalytic cracking?

  • alkanes passed over hot zeolite catalyst (aluminium oxide and silicon oxide)
  • this cracks the alkane into alkane and alkene
• What is steam cracking?

  • Steam is used to break alkanes into alkanes and alkenes
• What is the functional group for alkenes?

  C=C
• What is the combustion of alkenes like?

  • don't completely combust like alkanes, normally incomplete combustion
  • Burn with smokey flames (CO is produced)
• How do alkenes react with hydrogen (hydrogenation), water (hydration) and the halogens?

  As alkenes C=C bonds (double covalent bonds) they open up their bonds to create single C-C bonds
• What does an alkene + hydrogen produce?

  an alkane
• what does an alkene + water produce?

  an alcohol
• What is the functional group for alcohols?

  OH
• What are the first 4 members of alcohols?

  Methanol,

  ethanol,

  propanol,

  butanol