PAPER 2

• Rate of reaction


  How quickly a reaction happens
• Mean rate


  The rate calculated as the change in quantity divided by time, as the rate could be changing over the time measured
• Experiment to measure rate of reaction

  1. Reacting hydrochloric acid and sodium thiosulfate in a conical flask

  2. Measuring time until solution becomes cloudy

  3. Repeating at different temperatures
• As temperature increases


  The time taken for the reaction decreases
• Experiment to measure rate of reaction

  1. Using a gas syringe to measure volume of gas produced

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


  Used to find the rate at any time by calculating the change in quantity divided by change in time
• Ways to 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 reaction


  Reaction where products can reform reactants
• Equilibrium


  Point where forward and reverse reaction rates are equal, so no overall change
• 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 is the result of plankton being buried under water a long time ago
• Hydrocarbons


  Molecules made up of only carbon and hydrogen atoms
• Alkanes


  Hydrocarbons with single carbon-carbon bonds
• Alkane names


  • Methane
  • Ethane
  • Propane
  • Butane
  • Pentane
  • Hexane
• Fractional distillation of crude oil

  1. Heating to evaporate

  2. Fractions condense at different heights in the column based on boiling points
• Fractions from fractional distillation

  • LPG (gases)
  • Petrol
  • Kerosene
  • Diesel oil
  • Heavy fuel oil
• Longer hydrocarbon fractions have higher viscosity
• Shorter hydrocarbon fractions are more flammable
• Alkenes


  Hydrocarbons with carbon-carbon double bonds
• Unsaturated


  Having a carbon-carbon double bond
• Testing for alkenes


  Adding bromine water, which turns colourless if an alkene is present
• Catalytic cracking


  Breaking down long alkanes into shorter alkanes and alkenes using a catalyst at 550°C
• Steam cracking


  Breaking down long alkanes into shorter alkanes and alkenes using high temperature (over 800°C) without a catalyst
• Alcohol


  Organic compound with an -OH functional group
• Carboxylic acid


  Organic compound with a -COOH functional group
• Addition polymerisation


  Joining together monomers with double bonds to form long chain polymers
• Condensation polymerisation


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


  Monomer with both amino (-NH2) and carboxyl (-COOH) functional groups, building blocks of proteins
• DNA


  Double helix polymer made from four different nucleotide monomers, stores genetic code
• Starch


  Natural polymer made from glucose monomers
• Cellulose


  Natural polymer made from beta-glucose monomers
• Melting point and boiling point


  Used to test if a substance is pure
• Formulation


  Mixture with specific quantities of different substances for a particular purpose
• Chromatography


  Technique to separate components of a mixture
• DNA


  It's made from two polymers that spiral around each other in a double helix and it's made from four different monomers called nucleotides
• 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