Paper 2

• Rate of reaction


  How quickly a reaction happens
• Mean rate


  The rate could be changing over the time you measure, but this is true for any measurement over time
• 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. Using a gas syringe to measure the volume of gas produced

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

  3. Drawing a tangent to find the rate at any point
• Factors that increase the rate of 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
• Organic compounds


  Compounds with a carbon backbone
• Crude oil is the result of plankton being buried under water a long time ago
• Alkanes


  Hydrocarbons with single-bonded carbon atoms and hydrogen atoms
• 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 the different fractions
• Fractions from fractional distillation

  • LPG (up to 4 carbons)
  • Petrol
  • Kerosene
  • Diesel oil
  • Heavy fuel oil
• Properties of fractions


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


  Hydrocarbons with a carbon-carbon double bond
• Unsaturated


  Having a carbon-carbon double bond
• Testing for alkenes


  1. Adding bromine water

  2. Colourless solution indicates the presence of an alkene
• Cracking


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


  Using a temperature of around 550°C and a zeolite catalyst
• Steam cracking


  Using a temperature over 800°C with no catalyst
• Alcohols


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


  1. Combustion to form carbon dioxide and water

  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 a double bond
• 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


  A large molecule that stores genetic code, made from two polymers that spiral around each other
• Starch and cellulose


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


  Tests to determine if a substance is pure
• Formulation


  A mixture designed for a specific purpose, with carefully controlled quantities of different substances
• Chromatography

  A technique for separating the components of 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
• Amino acids


  Monomers that make up proteins