organic chemistry

• what is cracking?

  a thermal decomposition reaction
• what are the 2 types of cracking called?

  1 catalytic cracking

  2 steam cracking
• what is the formula for alkanes?

  CnH2n+2
• what is the formula for alkenes?

  CnH2n
• how does catalytic cracking work?

  1. heat the hydrocarbons- vaporise
  2. pass vapour over hot powdered aluminium oxide(catalyst)
  3. as they come into contact with the catalyst the long hydrocarbons split into 2 smaller hydrocarbons
• how does steam cracking work?

  1. heat the hydrocarbons- vaporise
  2. mix vapour with steam
  3. heat the mixture up to very high temperatures
  4. causes long chains to split into smaller ones
• what is the cracking equation?

  long chain alkane --> shorter alkane + alkene
• what is the test for alkenes?

  Bromine water test, goes orange to colourless if present
• what are alkenes added together to make?

  Polymers (plastics)
• what is crude oil made from?

  plankton
• how is crude oil separated?

  Fractional distillation
• what do crude oil contain a mixture of?

  Hydrocarbons
• what are hydrocarbons?

  a compound of hydrogen and carbon ONLY
• what are alkanes?

  Hydrocarbons with single bonds. they are a saturated substance which means they can't form new bonds with other substances
• what are the first 4 alkanes?

  1. methane
  2. ethane
  3. propane
  4. butane
• what is the 1st stage in fractional distillation?

  heating the crude oil
• why do longer chains have higher boiling points?

  they have more weak intermolecular forces so they require more energy to overcome the forces
• what are alkenes?

  Hydrocarbons with at least 1 carbon double bond, they are unsaturated which means they can form new bonds to other substances