paper 2

• Rate of reaction


  How quickly a reaction happens
• Mean rate


  The rate could be changing over the time you measure, so this technically gives you the mean rate
• Experiment to measure rate of reaction

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

  2. Measuring the time until the solution becomes cloudy (increased turbidity)

  3. Repeating at different temperatures
• As temperature increases


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

  1. Measuring the volume of gas produced using a gas syringe

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

  3. Drawing a tangent to find the rate at any time
• Ways to increase the rate of a reaction

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


  Reactions where the products can return to the original reactants
• Equilibrium


  The 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 and vice versa
• Crude oil


  Mixture of hydrocarbons formed from buried plankton
• Alkanes


  Hydrocarbons with single-bonded carbon atoms
• Alkane names


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

  1. Heating to evaporate

  2. Condensing at different heights based on boiling points

  3. Collecting different fractions (LPG, petrol, kerosene, diesel, heavy fuel oil)
• Alkane fractions


  • Shorter fractions are more flammable
  • Longer fractions are more viscous
• Alkenes


  Hydrocarbons with carbon-carbon double bonds
• Unsaturated


  Having a carbon-carbon double bond
• Testing for alkenes


  1. Adding bromine water

  2. Colourless solution indicates presence of alkene
• 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 (complete)

  2. Combustion to CO and H2O (incomplete)

  3. 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
• Amino acids


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


  Double-helix polymer made from nucleotide monomers that stores genetic code
• Starch and cellulose


  Natural polymers made from glucose monomers
• Formulation


  A mixture designed to have specific useful properties
• Chromatography


  A technique for separating substances in a mixture
• Polymer


  Molecules made from a large number of monomers joined together in a chain
• Nucleotides


  Four different monomers that make up DNA
• Starch


  Natural polymer where the monomer is glucose
• Cellulose


  Polymer made from beta glucose
• Proteins


  Polymers made from amino acid monomers
• Melting point/Boiling point


  Way to tell if a substance is pure - should be a very specific temperature
• Formulation


  Mixture that has been specially designed to be useful in a very specific way with very specific quantities of different substances
• Chromatography


  1. Separating substances in a mixture

  2. Stationary phase (e.g. chromatography paper)

  3. Mobile phase (e.g. water) rises up paper due to capillary action

  4. Draw line at bottom in pencil

  5. Measure how far solvent and substances have moved to calculate Rf value
• Rf value is a ratio of how far a spot has moved compared to the solvent, between 0 and 1