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
• 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
• Factors that increase rate of reaction

  • Increasing concentration of reactants
  • Increasing pressure of gas reactants
  • Increasing 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
• 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


  Mixture of hydrocarbons formed from buried plankton
• Alkanes


  • Molecules made up of only carbon and hydrogen atoms in a chain
  • General formula: CnH2n+2
• Fractional distillation of crude oil

  1. Heating to evaporate and separate into fractions based on boiling points

  2. Shorter alkanes remain as gases, longer ones condense at different heights
• Fractions from crude oil

  • 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 decolourises 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
• Carboxylic acids


  Organic compounds with a -COOH functional group
• Oxidation of alcohols


  Forming carboxylic acids without combustion
• Amino acids


  Organic compounds with both an amino (-NH2) and a carboxyl (-COOH) group
• DNA


  Large molecule that stores genetic code, made from two polymer strands in a double helix
• Starch and cellulose


  Natural polymers made from glucose monomers
• 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
• Melting point


  A way to tell if a substance is pure - it should be a very specific temperature
• Boiling point


  A way to tell if a substance is pure - it should be a very specific temperature
• Formulation


  A mixture that has been specially designed to be useful in a very specific way
• Chromatography


  1. Separating substances in a mixture

  2. Stationary phase (often paper)

  3. Mobile phase (often water)

  4. Measure distance moved

  5. Calculate RF value
• Hydrogen test: Squeaky pop with burning splint
• Oxygen test: Relights glowing splint
• Carbon dioxide test: Turns lime water cloudy