Topic 7

• what is a hydrocarbon?

  a compound made of hydrogen and carbon atoms
• Alkanes


  a hydrocarbon containing only single covalent bonds

  - fully saturated

  
• first 5 alkanes


  1. Methane

  2. Ethane

  3. Propane

  4. Butane

  5. Pentane
• Hydrocarbon properties change as the chain gets longer

  Shorter chain = more runny

  Longer chain = viscous

  
  

  Shorter chains = lower BP's

  
  

  Shorter chain = more flammable
• Complete combustion equation


  hydrocarbon + oxygen --> carbon dioxide + water
• Fractional distillation steps


  - crude oil is heated to boiling,

  - vapour passes into fractionating column (in this column there is a TEMPERATURE GRADIENT),

  - temperature decreases up the tower,

  - diff fractions condense at diff heights,

  - longest chain does not condense and runs out the bottom to form bitumen

  - longer chains condense at the bottom,

  - shorter chains condense at the top
• Fractional distillation

  
• Crude oil uses


  Oil provides the fuel for most modern transport

  = cars, train, planes etc

  
  

  The petrochemical industry uses some of the hydrocarbons from crude oil as a feedstock to make new compounds for use in things like polymers, solvents, lubricants, and detergents

  
  

  All products from crude oil are organic compounds (compounds w/ carbon atoms)

  = as carbon atoms can bond together to form different groups called homologous series

  = these groups contain similar compounds with many properties in common
• Cracking Hydrocarbons


  Breaking up of large hydrocarbon molecules into smaller and more useful molecules
• What does cracking hydrocarbons form

  a shorter ALKANE and ALKENE
• Alkenes


  have a C-C double bond as their functional group

  - more reactive because of this

  
• first 4 Alkenes


  Ethene

  Propene

  Butene

  Pentene
• Burning Alkenes


  - smoky flame

  - less energy released

  - need a lot of oxygen to completely combust

  - usually undergo INCOMPLETE COMBUSTION
• Burning Alkenes equation


  alkene + oxygen ---> carbon + carbon monoxide + carbon dioxide + water
• Addition Reactions in Alkenes

  Alkenes can react with:

  - Hydrogen

  - Water

  - Halogens

  
• Alkenes + Hydro


  - Hydrogenation

  - (reacted in presence of a catalyst)
• Alkene + steam


  - forms an alcohol

  
• Alkene + Halogen


  they can reaction together as the halogens are all diatomic molecules

  
• Addition Polymers


  - made from unsaturated monomers

  - c=c bond opens up to join to another opened up carbon atom

  - makes polymer chains

  - poly(name of monomer)
• uses of polymers


  Poly(ethene) = light = plastic bags, bottles and other containers

  Poly(propene) tough = kettles and carpets
• Drawing a polymer

  
• Alcohols


  - functional group is OH

  
• alcohols general formula

  
• first 5 alcohols


  Methanol,

  Ethanol,

  Propanol,

  Butanol,

  Pentanol
• (first 4) alcohols properties

  - flammable - complete combustion

  - all soluble in water

  - react with sodium

  - can be oxidised to form carboxylic acids
• Alcohol uses


  - solvents because they dissolve things water can't

  - fuels e.g. spirit burners because they burn cleanly
• what is fermentation?


  the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms,

  
  

  sugar -----> ethanol + carbon dioxide

  yeast
• Carboxylic acids


  - functional group is -COOH
• first 4 carboxylic acids

  Methanoic acid

  Ethanoic acid

  Propanoic acid

  Butanoic acid
• first 4 carboxylic acids (drawn)

  
• Carboxylic acids reactions


  - React like any other acids with carbonates to form salt + water + CO2

  - the salts formed end in -anoate

  - can dissolve in water but they ionise and release H+ ions

  
  

  ETHANOIC ACID + SODIUM CARBONATE -----> SODIUM ETHANOATE + WATER + CARBON DIOXIDE
• Esters


  - made from carboxylic acid + Alcohol

  - functional group -COO-

  - an acid catalyst is used
• alcohol + carboxylic acid ---->

  ester + water
• drawing Ethyl Ethanoate

  
• Condensation polymers


  polymers containing different functional groups

  monomers form bonds e.g. polyester.

  - each new bond that forms releases a small molecule.
• Making a polyester

  
• Addition Polymerisation


  - ONE MONOMER type containing a double C-C bond

  
  

  - ONE PRODUCT

  
  

  - CARBON-CARBON double bond
• Condensation polymerisation


  - 2 MONOMER TYPES with same functional group

  or

  - ONE MONOMER with 2 different functional groups

  
  

  - 2 TYPES OF PRODUCT

  
  

  - 2 REACTIVE GROUPS on each monomer
• Naturally occurring polymers examples

  - Proteins

  - DNA molecules

  - Simple sugars
• Proteins


  - polypeptides

  - every new bond formed a water molecule is lost

  - used in human bodies - catalysts, antibodies

  - made of amino acids