Alkenes C2H4 C3H6 What’s the What’s the formula for general these? formula for CnH2n alkenes?
Test for an unsaturated hydrocarbon (an alkene) Shake
CrackingHydrocarbons with shorter carbon chains are moreuseful, so sometimes we cut longer chains into shorterones using the process of cracking.A long alkane is heated, vaporised and passed over aceramic catalyst to produce a shorter alkane and analkene. C8H18 → C4H10 + C4H8 C10H22 → C7H16 + C3H6NoteAny combination of alkene and alkane can be made, includingstraight and branched chains, so long as the numbers of atomsbalance.
Hydrocarbons are compounds made of only hydrogen andcarbon atoms.Hydrocarbons – for example methane (CH4) – burn very well producingonly carbon dioxide (CO2) and water (H2O): CH4 + 2O2 → CO2 +2 H2OAlkanesThese are the simplest hydrocarbons. They are ‘saturated’ which meansthey only contain single bonds. They are pretty unreactive but burn wellmaking them good fuels.AlkenesThese are hydrocarbons containing a C=C double bond. The double bondmakes them quite reactive and they are used as a starting material tomake many other organic compounds.
The equation below shows the cracking of a hydrocarbon compound into two different compounds, A and B.State two differences between the structures of compounds A and B. Compound A has fewer C atoms or Compound B has fewer H atoms Compound A is reactive Compound A has C = C/double bond or can be used to make or Compound A is unsaturated many substancesWhy is compound A useful in industry? or can be used in polymerisation/making plastics/named plastic or can be used as a fuel
In 1939 Roy Plunkett opened the valve on a new cylinder of tetrafluoroethenegas. No gas came out! He cut the cylinder open and found that the gas had changed into a white solid. This solid was an addition polymerGive the name of the addition polymer that formed inside the cylinder. poly(tetrafluoroethene) or polytetrafluoroetheneThe structure of this polymer can be represented by the diagram below. Draw the structure of the monomer, tetrafluoroethene, from which it is formed
The diagram shows an apparatus that can be used to carry out crackingreactions in a laboratory.Why is aluminium oxide or broken porcelain used? catalyst or speeds up the reaction
Paraffin contains decane. The cracking of decane can be represented by theequation below. A decane molecule is split into two smaller molecules.Complete the equation by adding the formula of the other product. C10H22 (l) →.................... (l) + C2H4 (g) decaneS