Infrared Spectroscopy

  • bonds absorb IR radiation 
  • absorbtion of IR is a at a particular frequency/wavelength dependant on the bond
  • this causes the bond to vibrate
  • the spectrum shows peaks of which frequency has been absorbed and where it occured 
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Describing a Catalyst

  • can be recovered chemically 
  • uncanged at the end of a reaction
  • speed up the reaction 
  • provides an alternative route with a lower activation enthalpy 
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Dynamic Equilibrium

  • rate of the forward reaction is equal to the rate of the backwards reaction
  • concentrations of the reactants and products stay the same
  • closed system
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  • sequence/series of reations 
  • products of one reaction become the reactants of another reaction 
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Why is the ozone broken down in the troposphere an

  • bonds are too strong to be broken down in the troposphere 
  • in the stratosphere the UV breaks the bonds and forms chlorine radicals 
  • these radicals catalyse the breakdown of the ozone
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CO2 production

  • generating electricity
  • producing steel and iron
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CO2 removal

  • react CO2 with lime
  • pump it into or bury it under the ocean
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  • allows food crops to be used for fuel
  • doesnt compete 
  • the prduction of food is not affected 
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Catalyst Poison

  • very strongly bonded molecules
  • irreversible 
  • reaction cannot happen
  • prevents reactants from getting to the surface
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Heterogeneous Catalyst

  • reactant and caalyst are different states
  • molecule is absorbed onto surface of catalyst
  • intramolecular bonds break
  • bonds form in the products
  • products leave the surface via diffusion
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Why do structural isomers have the same enthalpy c

  • same number of bonds broken/made
  • same type of bonds broken/made
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Obtaining Enthalpy Value

  • burn a measured mass of fuel
  • measure the temperature rise
  • fixed mass of water
  • E = mct
  • scale to one mol
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Measurements needed to obtain Enthalpy Value

  • Ar of elements
  • specific heat capacity of water
  • mass/volume of water
  • mass of fuel burnt
  • temperature change
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Why is the real enthalpy change different to the c

  • heat lost to surroundings
  • incomplete combustion
  • evaporation/ loss of fuel
  • bond enthalpies in data book are averages
  • bond enthalpies in data book are gases
  • your experiment might not be standard conditions 
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Group 2 and Limewater Experiment

  • heat carbonates and pass the gas through limewater
  • use the same sumber of moles for the carbonates
  • same volume of limewater
  • same heating conditions
  • lime water goes cloudy
  • less cloudy as you move down the group
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Molecule Shape and Angle

  • state bond angle
  • x areas of electron density around the central atom
  • repeal each other as far apart in space as possible
  • minimise electron repulsion
  • state shape
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Atomic Emission Spectroscopy

  • electrons absorb energy
  • become excited and are promoted to a higher energy level
  • drops back down and emits light in the form of photons
  • the frequency of this light is specific to the energy gap
  • the gaps between energy levels are different for every element
  • hence the unique emission diagram
  • E = hv gives the energy emitted
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