Developing Fuels

Calculations from equations
1. Masses
  1. Mass=RAM x Mols
2. Volume of Gases
  1. The volume of 1 mole of a gaseous substance is 24dm^3 at room temperature (298 K) and pressure of 1 atmosphere pressure
  2. Number of moles = Volume in dm^3/24
Enthalpy and Entropy
1. Enthalpy
  1. Hess's Law
    1. As long as the starting and finishing points are the same, the enthalpy change for a chemical reaction will always be the same, no matter the route.
  2. Endothermic
    1. Reaction takes energy in from surroundings
    2. Energy released by making bonds is less than energy required breaking bonds
    3. Positive enthalpy change
    4. Temperature of surroundings decreases
  3. Exothermic
    1. Reaction gives out energy from the system to the surroundings.
    2. Temperature of surroundings increases
    3. Negative enthalpy change
    4. Energy released by making bonds is greater than energy required breaking bonds
2. Entropy
  1. Entropy is a measure of the number of ways In which particles can be arranged
  2. Gases have greater entropy than liquids; liquids have greater entropy than solids
  3. Mixtures have a greater entropy than unmixed constituents
  4. If the number of particles increases during the course of the reaction then entropy usually increases
Bond Enthalpies
1. Bond enthalpy is the average energy required to break the bonds in 1 mole of gaseous compounds
  1. If experimental enthalpy change is different it is usually because bond enthalpies are averaged and are for gaseous compounds
2. Bond Strengths
  1. The greater the bond enthalpy the stronger the bond
  2. Short bonds are stronger than long ones
  3. C=C is shorter and stronger than C-C
3. Bond breaking is endothermic so positive
4. Bond making is exothermic so negative
Alcohols and Ethers
Alkanes and other Hydrocarbons
Auto-ignition and octane numbers
1. Enter text here
Catalysts
Structural Isomerism
Pollution from cars
1. Pollution from Petrol
  1. Unburnt Hydrocarbons, CxHy
    1. Evaporative emissions and incomplete combustion
      1. Causes photochemical smog which causes respiratory problems
        Reduced by catalytic converters and oxygenates but this increases CO2
  2. Carbon Monoxide, CO
    1. Incomplete combustion of hydrocarbons
      1. Toxic to us, it decreases the uptake of oxygen by blood
        Reduced by catalytic converters and oxygenate
  3. Carbon Dioxide, CO2
    1. Complete combustion of hydrocarbons
      1. Causes enhanced green house effect and global warming
        Hydrogen is the only petrol alternative which doesn't produce CO2
  4. Sulfur oxides, SOx
    1. Sulfur in petrol reacts with oxygen in the air in the heat of the engine
      1. Causes acid rain which erodes limestone buildings and damages forests and lakes
        Low sulfur petrol can be produced by desulfurisation
  5. Nitrogen oxides, NOx
    1. Nitrogen from air reacts with oxygen from air in high temperatures of the engine
      1. Causes smog which causes respiratory problems. It also causes acid rain
        Reduced by Catalytic converters and reduced in lean burn engines but this may mean CxHy is increases
2. Alternative to petrol
  1. Diesel is unsustainable and produces more nitrogen oxides and particulates the only benefit is that it produces less CO and that its already sold at petrol stations
  2. Autogas produces less CO, CO2, CxHy and NO than a petrol engine and petrol engines can be easily converted but it is unsustainable and needs to be stored under pressure so that It is a liquid
  3. Ethanol produces less CO, CO2 and NO, it also has a high octane number and is carbon neutral. But it isn't completely sustainable as it requires large amounts of energy for cultivating sugar cane for fermentation. It is also highly flammable
  4. Biodiesel is sustainable as it can be made from waste plants and animal oils and fats, it is also carbon neutral and produces less CO, CxHy, SO2 and particulates than a diesel engine but NO emissions are higher
  5. Hydrogen only produces H2O as a waste product and is also completely renewable the only downside is that it is highly flammable so it need to be stored in high pressure fuel tank to keep it in liquid form
3. Energy Density= enthalpy of combustion x number of moles of fuel in 1 kg

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Developing Fuels

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