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- Created by: Gregory Brewster
- Created on: 18-02-15 14:24
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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Propagorion
- 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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Biofuels
- 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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