organic chemistry

• what is crude-oil


  non-renewable source thats a mixture of a large number of compounds, mainly hydrocarbons
• how is crude oil formed

  1 ) plankton buried in heat and pressure from sands so it breaks down to oil

  2 ) remains of sea creatures that died millions of years ago and were buried years ago
• what are hydrocarbons made up of

  hydrogen + carbons
• what are alkanes


  * hydrocarbons with only single carbon-carbon bonds

  * saturated hydrocarbons because no more hydrogen atoms can be added
• general formula for alkanes


  CnH(2n+2)
• first four alkanes


  methane

  ethane

  propane

  butane
• what is viscosity


  how runny a liquid is
• how does boiling point affect length of hydrocarbon

  longer hydrocarbons have higher boiling points
• how does viscosity affect hydrocarbon length

  longer chain hydrocarbons have a higher viscosity (stickier)
• how does flammability affect hydrocarbon length

  longer chains are less flammable
• how does volatility affect hydrocarbon length

  longer chains are less volatile
• what is volatility


  how easily a liquid turns into a gas
• what is combustion


  a reaction in which a fuel burns in oxygen
• what do hydrocarbons produce when they are burnt

  co2 + h2o
• what is the test for limewater - products of combustion


  limewater turns from colourless to cloudy
• what are the tests for water - products of combustion

  1 ) place test tube in ice and if water vapour condenses, water is present

  2 ) cobalt chloride paper goes from blue to pink
• why does incomplete combustion occur

  lack / no oxygen
• what comes off the flame in incomplete combustion

  black soot
• what can be produced in incomplete combustion and why is is bad

  carbon monoxide - starves your body of oxygen as binds to haemoglobin in blood
• products of incomplete combustion

  water + carbon monoxide
• what is cracking


  break long chain hydrocarbons into short chain alkanes and alkenes
• what are short chain alkanes used for

  fuels
• what are short chain alkenes used for

  polymers (plastic)
• why are short chain hydrocarbons wanted

  more useful and there is a high demand for them
• why are long chain hydrocarbons cracked

  less useful and is usually a lot left over
• what are the two types of cracking

  catalytic cracking

  steam cracking
• what type of process is cracking

  thermal decomposition
• how does catalytic cracking work

  catalyst heated first, and then the hydrocarbon which will flow through the catalyst as a gas and cracking will occur
• what are the products of catalytic cracking

  1 ) oily liquid product

  2 ) gaseous product (short alkane or alkene)
• what catalyst is used in catalytic cracking

  aluminium oxide catalyst

  silicon dioxide catalyst
• what is the hydrocarbon in

  ceramic wool is soaked in the hydrocarbon
• where is the hydrocarbon and where is the catalyst in catalytic cracking

  hydrocarbon - end of test tube in wool

  catalyst - middle of test tube so hydrocarbon flows through it
• how does steam cracking work

  hydrocarbon is mixed with steam and heated to a very high temperature
• how to test for alkanes and alkenes

  1 ) add alkane and alkene to different test tubes

  2 ) add a few drops of bromine water to each

  3 ) shake

  4 ) results are present
• what colour is bromine water and what is its symbol

  Br2 (aq) - orange
• what colour does alkanes go with bromine water

  no colour change - orange
• what colour do alkenes go with bromine water

  turns colourless because its decolourises bromine water as its more reactive
• are alkenes or alkanes more reactive and why

  alkenes because more hydrogen atoms can be easily added to the carbons in the double bond
• what are alkenes


  unsaturated hydrocarbons which have at least one carbon=carbon double bond
• what is the general formula for alkenes

  CnH(2n)