Organic Chem

• Crude oil

  Finite resource found in rocks, remains of ancient biomass consisting mainly of plankton buried in mud
• Crude oil

  Mixture of a very large number of compounds, where the chemical properties of each substance are unchanged
• Separating substances in crude oil

  Physical methods including distillation
• Hydrocarbons

  Molecules made up of hydrogen and carbon only, most are saturated hydrocarbons called alkanes
• Alkanes

  General formula: CnH2n+2
• First 4 alkanes

  • Methane, ethane, propane, butane (MEPB: Monkeys Eat Peanut Butter)
• Fractional distillation

  Oil is heated in fractionating column, vaporised oil evaporates and condenses at different temperatures
• Fractions from fractional distillation

  Contain molecules with similar number of carbon atoms
• Fuels produced from crude oil

  • Petrol, diesel oil, kerosene, heavy fuel oil, liquefied petroleum gases
• Materials produced by petrochemical industry

  • Solvents, lubricants, polymers, detergents
• The vast array of natural and synthetic carbon compounds occur due to the ability of carbon atoms to form families of similar compounds
• Properties of hydrocarbons

  • Shorter molecules are less viscous, lower boiling point, more flammable
• Hydrocarbons are burnt to produce energy, reaction produces carbon dioxide and water
• Cracking of hydrocarbons

  Heating to vaporise and passing over hot catalyst (catalytic cracking) or mixing with steam and heating (steam cracking)
• Alkenes

  Unsaturated hydrocarbons produced by cracking, have general formula CnH2n and at least one double carbon-carbon bond
• First 2 alkenes

  • Ethene, propene
• Alkenes react with bromine water, turning it from orange to colourless, while alkanes do not
• Alkenes are used for producing other chemicals, e.g. polymers
• Cracking reactions

  Must have same number of carbons and hydrogens on each side of equation
• Alkenes

  Have general formula CnH2n, contain at least one carbon-carbon double bond, making them unsaturated
• First 4 alkenes

  • Ethene, propene, butene, pentene
• Reactions of alkenes

  • Combustion, addition of hydrogen, water, halogens to form single carbon-carbon bond
• Alcohols

  Contain the functional group -OH
• First 4 alcohols

  • Methanol, ethanol, propanol, butanol
• Alcohols burn in air, dissolve in water to form neutral solutions, react with sodium to produce hydrogen and a salt, react with oxidising agents to form carboxylic acids
• Uses of alcohols

  • Methanol: chemical feedstock, anti-freeze, biodiesel

  Ethanol: alcoholic drinks, solvent, fuel

  All 4: fuels
• Producing ethanol

  Fermentation of sugar with yeast, 35°C, anaerobic, yeast enzyme catalyst
• Carboxylic acids

  Have the functional group -COOH
• First 4 carboxylic acids

  • Methanoic acid, ethanoic acid, propanoic acid, butanoic acid
• Carboxylic acids dissolve in water to produce acidic solutions, react with metal carbonates to produce carbon dioxide, a salt and water, react with alcohols to produce esters
• Carboxylic acids do not ionise completely in solutions, so have higher pH than strong acids of same concentration
• Addition polymerisation


  Many small molecules (monomers) join together to create very large molecules (polymers)
• The repeat unit in addition polymers has the same atoms as the monomer
• Condensation polymerisation


  Monomers with two functional groups react, losing small molecules such as water, to join together
• Amino acids

  Have an amine group and a carboxylic acid group, react by condensation polymerisation to produce polypeptides
• DNA (deoxyribonucleic acid)

  Large molecule essential for life, encodes genetic instructions
• Other naturally occurring polymers

  • Proteins (monomer = amino acid), cellulose (monomer = glucose), starch (monomer = glucose)
• Acids have more H+ than OH- ions, resulting in a lower pH value.
• A solution with a pH value of 7 has an equal number of hydrogen (H+) and hydroxide (OH-) ions present.
• The pH scale is logarithmic, so the difference between two values on the scale is equal to one unit.