Chemistry 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 taken for the solution to become cloudy

  3. Repeating at different temperatures
• As temperature increases

  The time taken for the reaction decreases
• Measuring 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
• 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 reactions


  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
• 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 covalent bonds, with the general formula CnH2n+2
• Alkane names

  • Methane (1 carbon)
  • Ethane (2 carbons)
  • Propane (3 carbons)
  • Butane (4 carbons)
  • Pentane (5 carbons)
  • Hexane (6 carbons)
• Fractional distillation of crude oil

  1. Heating to evaporate

  2. Fractions condense at different heights in the column due to different boiling points

  3. Collecting the different fractions
• Crude oil fractions

  • LPG (gases up to 4 carbons)
  • Petrol
  • Kerosene
  • Diesel oil
  • Heavy fuel oil
• Viscosity

  How thick and gloopy a liquid is
• Longer alkane fractions have higher viscosity
• Shorter alkane fractions are more flammable
• Alkenes

  Hydrocarbons with a carbon-carbon double bond
• Unsaturated

  Having a carbon-carbon double or triple bond
• Testing for alkenes

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

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

  1. Using a zeolite catalyst at around 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 produce CO2 and H2O

  2. Reaction with sodium to produce 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 of nucleotides
• 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
• 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