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 volume of gas produced using a gas syringe
• Graph of quantity vs time

  • Curve that starts off steeply but then levels out or plateaus, showing the reaction has completed
• Tangent


  Draw a tangent to the curve 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 the same, so there is no overall change
• Le Chatelier's principle


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


  Favours the forward reaction in a reaction with more moles of gas on the reactant side
• Increasing temperature


  Favours the endothermic (reverse) reaction
• In a reversible reaction, if the forward reaction is exothermic, the reverse reaction must be endothermic, and vice versa
• 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, then condensing at different heights based on boiling points

  2. Collecting the different fractions (LPG, petrol, kerosene, diesel, heavy fuel oil)
• Viscosity


  Measure of a liquid's thickness or resistance to flow
• 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 the alkene is present
• Alcohols


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


  Complete combustion produces CO2 and H2O, incomplete combustion produces CO and H2O
• 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


  Large molecule that stores genetic code, made from two polymers of nucleotides in a double helix
• 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 to have specific, useful properties
• Chromatography


  A technique to separate 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
• Melting point or boiling point


  A way to tell if a substance is pure or not
• Formulation


  A mixture that has been specially designed to be useful in a very specific way with very specific quantities of different substances used to make things like paints, fuels, alloys, fertilizers
• Chromatography


  1. Separating sub substances in a mixture

  2. Stationary phase (often special chromatography paper or filter paper)

  3. Mobile phase (often just water) rises up the paper due to capillary action dragging lighter particles further up

  4. Draw a line at the bottom in pencil so it doesn't move with the solvent

  5. Measure how far the solvent has moved and how far the substance(s) have moved to calculate an Rf value (retention factor)
• Rf value is a ratio of how far a spot has moved compared to the solvent, between 0 and 1