chemistry paper 2

• Rate of reaction


  How quickly a reaction happens
• Measuring rate of reaction

  1. Reacting hydrochloric acid and sodium thiosulfate

  2. Measuring time until solution becomes cloudy

  3. Repeating at different temperatures
• As temperature increases


  The rate of reaction increases
• Measuring rate of reaction

  1. Using gas syringe to measure volume of gas produced

  2. Plotting graph with quantity on y-axis and time on x-axis
• Tangent on graph


  Used to find rate at any time
• Factors that increase rate of reaction


  • Increasing concentration of reactants
  • Increasing pressure of gas reactants
  • Increasing surface area of solid reactants
  • Increasing temperature
  • Adding a catalyst
• Reversible reactions


  Reactions where products can return to reactants
• Equilibrium


  Point where forward and reverse reaction rates are equal
• Increasing pressure


  Favours forward reaction in equilibrium
• Increasing temperature


  Favours endothermic (reverse) reaction in equilibrium
• In a reversible reaction, if the forward reaction is exothermic, the reverse reaction must be endothermic
• Crude oil


  Result of plankton being buried under water a long time ago, consists mostly of hydrocarbons
• Alkanes


  Hydrocarbons with single-bonded carbon atoms in a chain, formula CnH2n+2
• Fractional distillation of crude oil

  1. Heating to evaporate and separate into fractions based on boiling point

  2. Longer alkanes have higher boiling points
• Fractions from fractional distillation

  • LPG
  • Petrol
  • Kerosene
  • Diesel oil
  • Heavy fuel oil
• Alkenes


  Hydrocarbons with a carbon-carbon double bond
• Unsaturated


  Having a carbon-carbon double bond
• Testing for alkenes


  Adding bromine water, which decolorises if an alkene is present
• Cracking


  Breaking down longer alkanes into shorter alkanes and alkenes
• Catalytic cracking


  1. Using a zeolite catalyst at 550°C

  2. Steam cracking at over 800°C with no catalyst
• Alcohols


  Organic compounds with an -OH functional group
• Reactions of alcohols


  1. Combustion to CO2 and H2O

  2. Reaction with sodium to form sodium alkoxide and hydrogen
• Carboxylic acids


  Organic compounds with a -COOH functional group
• Addition polymerisation


  Joining together monomers with double bonds
• Condensation polymerisation


  Joining together monomers with two functional groups, releasing water
• Amino acids


  Organic compounds with both amino (-NH2) and carboxyl (-COOH) groups
• DNA


  Double-stranded polymer of nucleotides that stores genetic information
• Starch and cellulose


  Natural polymers made from glucose monomers
• Melting point and boiling point


  Used to test purity of substances
• Formulation


  Mixture designed for a specific purpose with specific quantities of components
• Chromatography


  Technique for separating components of a mixture
• Double helix


  Made from two polymers that spiral around each other
• Nucleotides


  Four different monomers that make up DNA
• Starch


  A natural polymer where the monomer is glucose
• Cellulose


  A polymer that's made from beta glucose
• Proteins


  Have amino acids as their monomers
• Melting point/Boiling point


  A way to tell if a substance is pure - it should be a very specific temperature
• Formulation


  A mixture that has been specially designed to be useful in a very specific way with very specific quantities of different substances
• Formulations


  • Paints
  • Fuels
  • Alloys
  • Fertilizers
• Chromatography


  A way of separating substances in a mixture