organic

• a hydrocarbon is a compound with only hydrogen and carbon
• a homologous series is a family of molecules with the same functional group so they have the same reactions and trends in their physical properties
• short hydrocarbon chain (less carbon atoms) = lowest B.P, least viscous, lighter colour, most flamable
• long hydrocarbon chain (more carbon atoms) = highest B.P, most viscous, darker colour, least flamable
• fractional distilation technique = crude oil is heated until vapourised and enters bottom of fractionating column, temperature gradient is hotter at bottom and cooler at top, vapour rises up column and condenses at boiling point and are collected
• isomerism?

  molecules with the same molecular formula but with a different structure
• incomplete combustion?

  • not enough oxygen available - produces carbon monoxide, carbon (soot) and water
• complete combustion?

  • is enough oxygen available - produces carbon dioxide and water
• carbon monoxide (body) = bonds to red blood cells and reduces the capacity of oxygen
• a functional group is an atom or group of atoms which giver a homologous series its characteristic chemical reaction - eg. c=c is the alkene functional group
• 3-4 carbons = refinery gases (domestic heating and camping gas) - cooler
• 6-9 carbons = petrol (car fuel)
• 11-16 carbons = kerosine (plane fuel)
• 14-20 carbons = diesel (lorry fuel)
• 20-27 carbons = fuel oil (ship boilers)
• >35 carbons = bitumen (road surface) - hotter
• crude oil practical:

  1. heat and vaporise crude oil
  2. passes into fractioning column
  3. hydrocarbon vapours travel up column
  4. condense at boiling point
• give two characteristics of a homologous series?

  • they have same general formula
  • similar chemical properties
  • a trend in physical properties