organic chemistry

• what is crude oil?

  Crude oil is a non-renewable resource that is a mixture of lots of different compounds (mostly hydrocarbons).
• Properties of hydrocarbons

  • longer chains = higher viscosity
  • longer chains= higher boiling-point
  • longer chains= less flammable
• where is crude oil found?

  Crude oil is found in rocks. It is made from fossilized remains of ancient plankton.
• what’s the bonding of alkanes

  In alkanes carbon atoms bond to 4 atoms they are called saturated hydrocarbons as they are all single bonds.
• why are alkanes used as fuel?

  they have low reactivity so they combust well
• what’s the formula for an alkane

  Cn H(2n+2)
• examples of alkanes

  • Methane (CH4)
  • Ethane (C2H6)
  • Propane (C3H6)
  • Butane (C4H10)
• what is fractional distillation?

  The process of separating crude oil into hydrocarbons with similar numbers of carbon atoms ( the name for these is “fractions”).
• what’s long-chain and short-chain hydrocarbons?

  Hydrocarbons with lots of carbon atoms are called long-chain hydrocarbons. and short-chain hydrocarbons are hydrocarbons with few carbon atoms. 
• why do we use fractional distillation to break hydrocarbons?

  Different hydrocarbons have different boiling points and fractional distillation separates the hydrocarbons using their different boiling points.
• steps of fractional distillation

  evaporation, condensation + collection
• how do you evaporate in fractional distillation

  Heating the crude oil vapor at the bottom of the fractionating column and it rises upwards
• condensation in fractional distillation

  The temperature is higher at the bottom. the long-chain hydrocarbons condense and are collected as liquids. Short-chain hydrocarbons condense at higher points as they condense at a lower temperature.
• collection in fractional distillation

  they are collected and creates fuel and other products (such as solvents, detergents, lubricants, etc.)
• Homologous series

  the list of different carbon-containing compounds 
• burning hydrocarbons without enough oxygen

  If alkanes are burned without enough oxygen then carbon monoxide can be created. 
• carbon monoxide equation

  2C + O2 -> 2CO
• carbon monoxide properties

  colourless, toxic, odourless
• alkanes burned with oxygen


  energy is created and carbon and hydrogen get oxidised creating carbon dioxide and water.
• why do heavy fractions of crude oil not make good fuels

  don’t ignite easy, low volatility, high boiling-point
• catalytic cracking

  Vaporised heavy hydrocarbons are passed over a heated catalyst. Produces alkanes and alkenes
• steam cracking

  Vaporised heavy hydrocarbons are combined with hot steams. Produces alkanes and alkenes 
• what is an alkene

  Alkenes are similar to alkanes in the fact they are hydrocarbons but they can be made into polymers and they are starting materials for chemicals such as ethanol.
• Alkenes

  Alkenes are hydrocarbons with the functional group C=C. This means that alkenes have a carbon-carbon double bond. They are reactive and unsaturated
• reactivity of alkenes

  C=C functional group means they are more reactive than alkanes
• Unsaturated hydrocarbons (alkenes)

  Contains a double bond (C=C)
• c=c

  This means that an alkane and alkene with the same length of carbon chain will have different numbers of hydrogen atoms - the alkane will have two more hydrogen atoms.
• Alkenes are a homologous series with the general formula 


  CnH2n-
• 4 smallest alkenes

  Ethene (C2H4) Propene (C3H6) Butene (C4H8) Pentene (C5H10)
• alkene reactions

  Addition reactions are normal for alkenes. In these reactions, the C=C bond opens up and allows carbon atoms to bond with new atoms.
• alkenes + oxygen

  Alkenes can be involved in combustion reactions with oxygen. The outcome of these reactions is similar to when other hydrocarbons react with oxygen. They burn with smokey flames
• Alkenes + halogens

  Alkenes will react if mixed with bromine water and shaken. This causes the solution to change colour from orange-brown to colourless. This is an effective test for distinguishing between alkenes and alkanes.
• Alkenes and water

  When a catalyst is present, alcohols can be formed by reacting alkenes with steam.
• Alkenes and hydrogen

  When a catalyst is present, alkanes can be formed by combining hydrogen with an alkene. Adding hydrogen atoms across a carbon-carbon double bond is called hydrogenation.
• The functional group of alcohols is a hydroxyl group (-OH).
• alcohols

  CnH2n+1OH
• 4 smallest alcohols

  Methanol (CH3OH), Ethanol (CH3CH2OH), Propanol (CH3CH2CH2OH), Butanol (CH3CH2CH2CH2OH)
• When alcohols are added to water, they dissolve to give neutral solutions.
• When alcohols and sodium react together, hydrogen is produced.
• When alcohols react with air (and heat), carbon dioxide and water are produced.