Developing Fuels.

Developing Fuels.

Entropy
1. Tells you how much disorder there is.
  1. Solids
    1. Lowest entropy . Particles have fixed points. Easy to predict where a particle will be.
  2. liquids
    1. Some disorder. Close together but can move freely not so orderly , harder to predict.
  3. gases
    1. Highest disorder. No order impossible to predict. Highest entropy.
2. Number of particles increase entropy.
3. Mixture of paritcles increases entropy.
Enthalpy Change
1. Energy transferred in a reaction at constant pressure units are Kjmol-1
2. Bond enthalpy is realted to length of bond.
  1. Distance between two nuceli is the distance of attractive and repluseive forces balance
Hess's Law
1. Total enthalpy change is independent of the route taken.
Catalyst's
1. Speed up a chemical reaction but can be recovered chemically unchanged after reaction.
2. Catalysis the speeding up of a reaction through the use of a catalyst.
3. Hetrogeneous catalysts are in different physical states from the reactants.
4. Long chain alkanes are cracked shorter usinf zeolite catalysits.
5. Reactions happen on hetrogeneous catalysts.
  1. 1. Reactant molecules arrive at the surface and bond with the solid catalysts = adsorption.
    1. 2.The bonds between reactant's atoms are weakened and break up foroming radicals
      1. 3. radicals join together to form new harmless moelcules.
        4. the new moelcules are then detached from the catalyst called desorption.
Experimental results errors
1. Incomplete combustion
  1. Fuel evaporated.
    1. Some heat will be absorbed by container
      1. Lost to surroundings
2. Accuracy
  1. How close results are to true value.
Fractional distillation.
1. 1. Crude oil is vapourised at 350*
  1. 2.It goes up the fractioning column
    1. 3. Because of different chain lengths each fraction condenses at different temperatures
      1. 4.The fractions are drawn off at different temperatures.
        If their boiling point is too high they end up as residue at the bottom and if their boiling point is too low they end up as gasses at the top
2. Cracking.
  1. Catlytic
    1. Uses zeolite catalyist , Slight pressure , 450* Cuts costs lower temp and speeds up
  2. Thermal.
    1. High Temp 1000* High pressure produces lots of alkenes make polymers eg polyethene
3. Isomerisation.
  1. Changes Stright chain alkanes into branched isomers.
    1. 1. Heat stright chain alkane with a Platinium Catalyst struck on inert alaminium oxide.
      1. 2.Molecule broken up and put together as a branched chain isomer.
        3. Zeolite acts as molecular sieve straight chain go through zeolite and are recycled.
4. Reforming.
  1. Converts alkanes into arenes requires platiinium catalyst struck on inert alaminium oxide
Fuels.
1. Burning fuels
  1. Unburnt hydrocarbons
    1. Oxides of nitrogen are produced when high temp in car cause nitrogen and oxy to react and they can react in sunlight to form groud level ozone photochemical smong can irritate eyes.
      1. Sulfur dioide dissovles in moisture to form acid rain.

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	Criado por Talentless Academic quase 11 anos atrás