Chemistry - Organic Chemistry

CRUDE OIL
1. mixture of large compunds, most hydrocarbons/nautral gas
  1. hydrocarbons - a compound madeup of hydrogen + oxygen atoms only
    1. homologous - CnH2n + 2, methane: CH4
    2. alkanes
      1. single bond, less reactive, not affected by acid/alkali
      2. burn well in O2, produce CO2 + H2O, lots of heat, used as fuels - propane/butane used for camping gas
      3. saturated, single covalent bond
    3. alkenes
      1. double bond, more reactive, made by crakcking
      2. unsaturated, double covalent bond
    4. test for hydrocarbons - bromine water
      1. alkane in bromine water - stays orange , if alkene placed - goes colourless, double bond - more reactive
2. fractional distillation
  1. separating crude oil into useable products
  2. larger molecules, higher b.p./m.p. viscous, difficult to light/burn, smoky flame
    1. smaller molecules, lower b.p./m.p. , easy to ignite, clean flame, runny/thin
  3. catalyst - substance able to speed up reaction w/o changing properties of substance or itself
  4. fraction - group of molecules w/ similiar b.p.
  5. fractionating column hot at bottom, cooler at top
    1. larger hydrocarbons turn into liquids at bottom, higher b.p.
      1. high temps, smaller hydrocarbons stay gas, rise up, condense
        some stay as gases, leave top
      2. require alot of heat
3. too many large, less useful hydrocarbons (bitumen) smaller hydrocarbons (petrol) more in demand
  1. cracking, big molecules broken down by heating, pass over catalyst
    1. always produces shortchain molecules, ethene
4. fossil fuel, million of years to form, tiny animals + plants lived in sea buried in mud
POLYMERISATION
1. condensation
  1. nylon - small molecule always given off, water/HCL, different functional groups
    1. esters (carboxylic acid + alcohol)
2. addition
  1. small repeating unit, 1 functional group
    1. from products of fractional distillation
    2. make plastic bags, food containers (poly(ethene)), ropes,loudspeakers (poly(propene)), pipes, film for fod/bottles (poly(chloroethene))
3. small, reactive molecules (monomers) join to make polymer, large no. of similar units
4. thermoplastics - soften easily, remoulded, weak forces between polymer chains
  1. thermoset - hard + rigid, heat strongly - break down + char, polymer chains fixed by strong bonds, cross links
    1. react w/ other monomers
5. advantages: don't rot, last a long time,
  1. disadvantages: take up space in landfills, burning causes pollution expensive (need high temps)
    1. plastics made by bacteria, biodegradable, expensive
    2. hydrogen cyanide forms when burning plastics w/ N2 in limited O2 supply
6. amino acids have 2 different function groups in molecule
  1. produce poly(peptides)
ALCOHOL
1. functional group OH
2. neutral when put in water
3. used for drinking, cleaning products,fuel
4. can produce ethanol 2 ways
  1. fermentation (yeast + plant based sugar)
    1. renewable, slow, not very pure, cheaper (don't need lots of heat) good in hot countries, beer
  2. hydration (ethene + steam + phosphoric acid (catalyst))
    1. non renewable, quick, more expensive (need lots of heat) 100% pure, cleaning products
      1. ESTERS
        functional group COO
        reaction of alcohol + carboxylic acid
        slow, carried out w/ concentrated acid (sulfuric acid)
        carboxylic acid + alcohol - ester + H2O
        distinctive smells, flavouring for foods, perumes
        1st part of name - alcohol
        2nd part - acid
        if alcohol = methanol and acid = ethanoic acid
        ester = methyl ethanoate
        volatile liquid = low b.p. + evaporate easily (to reach scent receptors)
CARBOXYLIC ACIDS
1. functional group COOH
2. weak acids
3. unpleasant tastes/smells
4. metal + carboxylic acid - salt + hydrogen
  1. salt always ends in ethanoate
    1. lighted splint to test for H2
5. carbonates + carboxylic acids = salt + H2O + CO2
  1. limewater to test if CO2 produced

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	Criado por Somto Ibeme mais de 6 anos atrás