chemistry paper 2

• Things that can increase the rate of a reaction

  • Increase surface area for solids
  • Increase concentration for solutions
  • Increase pressure for gases
• Things that can increase the rate of a reaction

  • Increase temperature
  • Use a catalyst
• Calculating rate of reaction from a graph

  1. Draw a tangent

  2. Find the gradient of the tangent

  3. Gradient = change in y / change in x
• Le Chatelier's principle


  If a system at equilibrium is subjected to a change, the system will adjust to counteract the change
• Increasing concentration or pressure


  Favours the reaction that makes the fewest moles
• Increasing temperature


  Favours the endothermic reaction
• Hydrocarbons


  Organic molecules that only contain carbon and hydrogen atoms
• Alkanes


  Hydrocarbons with only single covalent bonds between carbon atoms
• Alkenes


  Hydrocarbons with a double covalent bond between carbon atoms
• Fractional distillation of crude oil

  1. Heated at the bottom

  2. Vaporized into gas

  3. Recondense at different heights due to different boiling points
• Complete combustion


  Hydrocarbon reacts with oxygen to make water and carbon dioxide
• Incomplete combustion


  Hydrocarbon reacts with less oxygen to make carbon monoxide or carbon
• Alkenes turn bromine water from orange to colourless
• Reaction of water with an alkane

  Makes an alcohol
• Oxidation of an alcohol


  Produces a carboxylic acid
• Cracking of an alkane

  1. Requires high temperature (550°C+ for catalytic, 800°C+ for steam)

  2. Always produces a shorter alkane and an alkene
• Addition polymerisation of propene

  Produces polypropene
• Making an ester


  Reaction of a carboxylic acid and an alcohol
• Condensation polymerisation


  Requires two different monomers with functional groups on both sides
• Monomers for condensation polymerisation

  • Alcohol with two -OH groups
  • Carboxylic acid with two -COOH groups
• Polymers from biological monomers

  • Amino acids (polypeptides/proteins)
  • Glucose (starch)
  • Beta-glucose (cellulose)
• Rf value in chromatography

  Ratio of distance moved by substance to distance moved by mobile phase
• Flame test colours for metals

  • Lithium - crimson
  • Sodium - yellow
  • Potassium - lilac
  • Calcium - orange-red
  • Copper - green
• Testing for metal ions in solution

  1. Add sodium hydroxide

  2. Observe colour of precipitate
• Tests for anions in solution

  • Carbonates - react with acid to produce CO2
  • Halides - add silver nitrate and nitric acid, form coloured precipitates
  • Sulfates - add barium chloride and hydrochloric acid, form white precipitate
• Tests for gases


  • Hydrogen - squeaky pop with lit splint
  • Oxygen - relights glowing splint
  • Carbon dioxide - turns limewater cloudy
  • Chlorine - bleaches blue litmus paper
• Atmospheric pollutants


  • Carbon monoxide - poisonous
  • Sulfur dioxide - causes acid rain
  • Nitrogen oxides - respiratory problems
  • Particulates - health issues
• Making potable water from fresh and salt water

  1. Fresh water - filter, sterilise

  2. Salt water - desalinate using distillation or reverse osmosis
• Traditional and new methods of obtaining pure metals from ores

  • Traditional - electrolysis, displacement reactions
  • New - phytomining, bioleaching
• Corrosion of iron, copper, aluminium

  • Iron - rusting (iron oxide)
  • Copper - copper oxide
  • Aluminium - aluminium oxide
• Preventing corrosion


  Use a sacrificial metal that corrodes preferentially
• Why alloys are stronger than pure metals

  Different sized atoms disrupt the crystal lattice, making it harder for layers to slide past each other
• Optimal conditions for the Haber process

  1. Temperature 450°C

  2. Pressure 200 atm

  3. Catalyst used
• Chemicals used to make NPK fertilizers

  • Ammonia (N)
  • Phosphate (P)
  • Potassium chloride/sulfate (K)