Chemistry Paper 2

• Activation energy


  The minimum amount of energy required for a reaction to occur
• High temperature


  Increases the rate of reaction
• Effect of high temperature on rate of reaction


  • Collisions occur more frequently
  • Particles have greater kinetic energy
  • Particle collisions are harder and more successful
• Dynamic equilibrium


  Forward and reverse reactions occur at the same time
• Catalyst


  A substance which speeds up the rate of reaction without being used up
• Catalysts


  • Offer an alternative reaction pathway with lower activation energy
• Reversible reactions


  Products react together to produce the original reactants
• Activation energy is lower with a catalyst
• Overall energy change in a reaction is the same with or without a catalyst
• First 4 Alkanes


  • Methane (CH4)
  • Ethane (C2H6)
  • Propane (C3H8)
  • Butane (C4H10)
• Alkanes


  Hydrocarbons containing hydrogen and carbon atoms only, with the formula CnH2n+2
• First 4 Alkenes


  • Ethene
  • Propene
  • Butene
  • Pentene
• Alkenes


  Hydrocarbons with C=C double bonds, with the formula CnH2n
• Saturated


  All C-bonds are single
• Unsaturated


  Contain C=C double bonds
• Fractional distillation of crude oil

  1. Crude oil is heated until it evaporates

  2. It rises, cools, and condenses

  3. Different fractions have different boiling points and condense at different positions in the fractionating tower
• Fractions from crude oil

  • Refinery gases
  • Petroleum
  • Kerosene
  • Diesel
  • Fuel oil
  • Bitumen
• Viscosity


  How runny a substance is
• Volatility


  How easily something turns into a gas
• Fuel


  A substance which releases energy when burnt
• Types of combustion


  • Complete combustion (plentiful oxygen, CO2 and H2O made)
  • Incomplete combustion (insufficient oxygen, CO and H2O made)
• Carbon monoxide


  • Toxic, combines with haemoglobin, prevents oxygen transport
• Carbon dioxide


  • Greenhouse gas, causes global warming, sea levels rise
• Nitrogen and oxygen react

  Forming nitrogen oxides, causing acid rain
• Sulfur impurities in crude oil

  Forming sulfuric acid, causing acid rain
• Acid rain


  Damages limestone buildings, makes lakes too acidic, damages trees
• Homologous series


  A family of compounds with the same functional group
• Examples of homologous series

  • Alcohols (OH)
  • Esters (COO)
  • Carboxylic acids (COOH)
• Ester reaction conditions


  Strong acid, catalyst
• Alcohols


  • Methanol
  • Ethanol
  • Propanol
  • Butanol
• Ester formation


  Ethanoic acid + methanol -> ethyl ethanoate + water
• Ester uses


  Perfumes, flavourings
• Alcohol uses


  Drinks, fuels
• Reaction of sodium and ethanol

  Sodium + ethanol -> sodium ethoxide + hydrogen
• Oxidation of ethanol


  Ethanol + oxygen -> ethanoic acid + water
• Polymer


  A large molecule formed from many monomers
• Monomer


  A small molecule which joins together to form a polymer
• Formation of polyester


  Diol + dicarboxylic acid -> polyester + water
• Components of DNA


  • Adenine
  • Thymine
  • Cytosine
  • Guanine
  • Sugar
  • Phosphate backbone
• Pure substance


  Made up of only one element or compound