Chemistry Paper 2

• Rate of reaction


  How quickly a reaction happens
• Mean rate


  The rate calculated by dividing the change in quantity by the 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 the 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 the rates of the forward and reverse reactions are equal, so there is no overall change
• Increasing pressure


  Favours the forward reaction in a reversible reaction
• Increasing temperature


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


  Mixture of hydrocarbons formed from buried plankton
• 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

  3. Collecting different fractions
• Crude oil fractions


  • LPG
  • 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


  1. Adding bromine water

  2. Colour changes from orange to colourless
• 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
• Cracking increases supply of shorter alkanes and produces alkenes
• 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, producing water as a by-product
• Amino acids


  Organic compounds with both an amino (-NH2) and a carboxyl (-COOH) group
• 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 with specific quantities of substances designed 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