Chem P2

• Calculating rate of reaction


  1. Quantity of reactant used (9)/(cm³)

  2. Time taken (s)

  3. Quantity of product formed (g)/(cm³)

  4. Time taken (s)
• Ways to measure rate of reaction


  • Volume of gas collected per unit time
  • Time taken for a colour change or a change in turbidity
  • Increase in temperature per unit time in the reaction mixture
  • Decrease in mass of a reactant per unit time
  • Increase in mass of a product per unit time
• Steeper the line


  Faster the reaction
• Comparing reaction rates


  • Produces the most product, starts off quickly and finishes the latest
  • Produces the 2nd most amount of product, starts off the fastest and ends the quickest
  • Produces the least amount of product, starts off the slowest and finishes the quickest
• Collision theory


  Chemical reactions happen when reactant particles collide, as long as there is sufficient energy to start a reaction
• Activation energy


  Minimum amount of energy needed to start a given reaction
• Factors affecting rate of reaction


  • Temperature (particles have more energy and move around quicker)
  • Concentration (more particles in a given volume, collide more frequently)
  • Pressure (more particles in a given volume, collide more frequently)
  • Surface area (more particles are exposed to the other reactants, more collisions)
  • Catalyst (provides a different pathway with a lower activation energy)
• Fractional distillation


  Used to separate crude oil
• Catalyst


  Substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change
• Crude oil is a mixture of hydrocarbons
• Hydrocarbons


  • Compounds that contain only hydrogen and carbon
• Crude oil is a finite (non-renewable) resource, remaining of organisms that died millions of years ago
• Equilibrium


  In a closed system, a reversible reaction will eventually reach equilibrium, where the forward and backward reactions are occurring at the same rate
• Fractional distillation of crude oil

  1. Crude oil enters a tall fractionating column

  2. Vapours from the heated crude oil rise through the column

  3. Vapours condense when they become cool enough

  4. Liquids are led out of the column at different heights
• Increase in pressure


  Shifts the equilibrium towards the side with fewer molecules
• Feedstock


  A raw material used to provide reactants for an industrial process
• Products from fractional distillation of crude oil

  • Petrol
  • Kerosene
  • Diesel
  • Heavy fuel oil
  • Bitumen
• Decrease in pressure


  Shifts the equilibrium towards the side with more molecules
• Alkanes


  • Saturated hydrocarbons with single bonds
  • Increasing boiling point and viscosity, decreasing flammability
• Increase in concentration of reactants


  Shifts the equilibrium towards the products
• Alkenes


  • Unsaturated hydrocarbons with double bonds
  • Very volatile, flow easily, ignite easily
• Decrease in concentration of reactants


  Shifts the equilibrium towards the reactants
• Cracking


  1. Breaking down large hydrocarbons into smaller ones to use as fuel

  2. Thermal decomposition

  3. Catalytic cracking

  4. Steam cracking
• Reasons for cracking: to match the supply of fractions with the demand for them
• Decrease in temperature


  Shifts the equilibrium in the exothermic direction
• Combustion


  Rapid reaction between a substance and oxygen that releases heat and light energy
• Increase in temperature


  Shifts the equilibrium in the endothermic direction
• Complete combustion: hydrocarbon + oxygen → carbon dioxide + water
• Incomplete combustion: hydrocarbon + oxygen → carbon + carbon monoxide
• Crude oil and its products are useful as feedstock for the petrochemical industry
• Hydrocarbons


  Compounds that only contain hydrogen and carbon
• Crude oil


  Mixture of hydrocarbons
• Crude oil


  • Finite (non-renewable)
  • Remains of organisms that lived and died millions of years ago
• Feedstock


  A raw material used to provide reactants for an industrial reaction
• Uses of crude oil

  • Fuels
  • Kerosene
  • Diesel
  • Petrol
  • Solvents
  • Lubricants
  • Detergents
• Alkanes


  Saturated hydrocarbons with single bonds
• Alkanes


  • Methane
  • Ethane
  • Propane
  • Butane
• Alkenes


  Unsaturated hydrocarbons with double bonds
• Alkenes


  • Methene
  • Ethene
  • Propene
  • Butene
• Fractional distillation


  1. Heating crude oil enters a tall fractionating column

  2. Vapours from the oil rise through the column

  3. Vapours condense when they become cool enough

  4. Liquids are led out of the column at different heights