Homologous series

Similar Compounds
1. Same general formula
2. Similar Molecular structures
3. Similar Chemical properties
4. The physical properties change gradually as the compounds increase in size
  1. Boiling points increase gradually with the size of the molecules
    1. Molecules with fewer carbon atoms have lower boiling points
5. Naming compounds in a homologous series
  1. METH-
    1. One carbon atom
  2. ETH-
    1. Two carbon atoms
  3. PROP-
    1. Three carbon atoms
Alkenes
1. General formula of CnH2n
2. Unsaturated
  1. C=C double bonds
Alkanes
1. Saturated
  1. NO C=C Double bond
2. General formula of CnH2n+2
Alcohols
1. CnH2n+1OH
  1. Always show the functional OH group
2. Methanol
  1. Ethanol
    1. Propanol
    2. Can be made by Fermentation
      1. Using yeast to convert carbohydrates into alcohol
        The fermentation of sugars
        Collected from plants
        Yeast contains an enzyme
      2. C6H12O6 ------> 2C2H5+2CO2
      3. How?
        Yeast and Carbohydrate
        sealed and warm container
        30 - 40°C
        Higher = Denatured enzymes
        Anaerobic conditions
        Because the oxygen converts the ethanol into Ethanoic acid, which is Vinegar
        Alcohol concentration reaches 10 - 20%
        Fermentation stops
        Yeast killed by alcohol
        Yeast will fall to the bottom of the container
        Alcohol collected from the top
        Can be distilled
        More concentrated alcohol
        Brandy distilled from wine
        Whisky is distilled from fermented grain
        Vodka distilled from fermented grain or potatoes
        How?
        Dilute solution from fermentation
        Separate mixtures by heating them
        Ethanol had a lower boiling point than water
        Ethanol evaporates first
        Then condenses in a Liebig condenser
      4. Pros
        Renewable resource used
      5. Cons
        Not great quality of Ethanol
        Expensive for what you get
    3. Can be made by reacting Ethene with Steam
      1. Ethene made by cracking crude oil
        Non Renewable resource!
      2. Cheap
        Not much is wasted
        Ethene is pretty cheap
        made continuously and quickly
        High quality Ethanol is made
        No need for further refining
      3. ethene + water (steam) -----> ethanol
    4. ALCOHOL
      1. Bad thing for the body
        Lowers inhibitions
        More likely to have unprotected sex
        STI
        Pregnancy
        Reduces the activity of the nervous system
        Unconsciousness
        Coma
        Death
        Reduced reaction times
        Binge Drinking
        Liver Disease
        Lower brain cell count
        Dehydration
        Damage to brain cells
        Memory loss
        Long term or short term
      2. Bad thing for society
        Lowers inhibitions
        More likely to commit a crime
        Drink Driving
        Accidents
        More people in A&E
        Violent Crime
        Increase in policing
        £££££££
        Alcoholism
        Family breakdown
        Loose Job
        Homeless
    5. Ethanol can be dehydrated to Ethene
      1. Ethanol steam passed over catalyst
        Aluminium
        Opposite reaction of ethene and steam
        ethanol ---> ethene + water
Carboxylic Acids
1. CnH2n+1COOH
  1. Always show the functional COOH group
2. Methanoic Acid
  1. Ethanoic Acid
    1. Propanoic Acid
    2. Is in vinegar
    3. If wine or beer is left open the ethanol is oxidised to make ethanoic acid
      1. ethanol + oxygen ----> vinegar + water
        CH3CH2OH + O2 -----> CH3COOH + H2O
3. Reactions
  1. Carbonate
    1. Ethanoic Acid + Sodium Carbonate ------> Sodium Ethanoate + Water
  2. Metal
    1. Ethanoic Acid + Magnesium -----> Magnesium Ethanoate + Hydrogen
  3. Base
    1. Ethanoic Acid + Sodium Hydroxide ------> Sodium Ethanoate + Water + Carbon Dioxide
4. Alcohol + Carboxylic Acid -------> Ester + Water
  1. Esters
    1. Functional group COO
    2. Often used in perfumes and flavourings
    3. Polyesters
      1. Polymers that contain the ester functional group
      2. Plastic Bottles
      3. Polyester fibres into fabric
      4. Can be recycled
    4. Ester + Alkali
      1. Soap
        In water, anions are formed
        Hydrophobic part
        Hates Water
        Loves fat
        Tail
        Hydrophillic part
        Likes water
        Head
        Small and ionic
        Let water and oil mix
        Surround the oli and form droplets
        Lift the oily stains out of the fabric
      2. Fat or oil + Alkali
      3. The oil or fat breaks down into glycerol and long chain carboxylic acids
        Carboxylic acid reacts with the Alkali
        Acid + Alkali ---> Salt + Water
  2. Ethanoic Acid + Ethanol -----> Ethyl Ethanoate + Water
Unsaturated oils
1. At least one C=C bond
2. Less viscous than saturated oils
  1. Can be changed to solid SATURATED oils by adding hydrogen
    1. Hydrogenated
      1. Need a Nickel catalyst
        Can be filtered out and used again
      2. fat
        oil that is solid at room temperature
    2. Margarine
      1. some of the margarine is still unsaturated
      2. Firm enough to spread
        But lower in saturates than butter

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Homologous series

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	Created by Clare Baker over 11 years ago