organic chemistry

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What is fractional distillation
separation of a liquid into fractions differing on boiling points
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what is the process of fractional distillation
oil is preheated,then passed into column,fractions condense at different heights,temperature column hottest at bottom, boiling point depends on size of molecules, small molecules condense at top larger at the bottom
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what does the separation depend on in the fractioning column
boiling point and the size of the molecules
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what does vacuum distillation allow
allows heavier fractions to be further separated without high temperatures
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what will lowering the pressure do over a liquid do to its boiling point
lower it
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what is cracking
it is the conversion of large hydrocarbons to smaller hydrocarbons by the breaking of C-C bonds
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what are the economic reasons for cracking
the petroleum fractions which are shorter chained hydrocarbons are in more demand,to make use of excess long hydrocarbons and turn them into something useful, products of cracking more valuable
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what are the conditions of thermal cracking
high temperature(400-900) and pressure (7000kPa)
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what does thermal cracking usually produce
Mostly alkenes and it sometimes produces alkanes
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what are the conditions of catalytic cracking
low pressure and high temperature(450) it also uses a zeolite catalyst
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what does catalytic cracking produce
branched and cyclic alkanes and making motor fuels.
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what are the products of complete combustion
water and carbon dioxide
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When alkanes burn is the reaction endo or exothermic
exothermic as heat energy is given out
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what are the products of incomplete combustion
carbon monoxide and soot
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how can sulfur dioxide be removed from the atmosphere
It can be removed by flue gas desulfurisation the gases pass through a scrubber containing calcium oxide which then reacts with acidic sulfur dioxide in a neutralisation reaction
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what is the other pollutant that causes acid rain
nitrogen oxides
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what are the pollutants that damage the earth
nitrogen oxides,carbon monoxide, carbon dioxide,unburnt hydrocarbons and soot
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what do catalytic converters do
They remove harmful gases and unburnt hydrocarbons from the exhaust system and turn them into harmless gases
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what is the metal used in the catalytic converter and why is it used
platinum or rhodium can be used and it is to give the honeycomb material a large surface area
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what is global warming causing
carbon dioxide is being released and it traps the earths infra red radiation in the atmosphere
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what is the reaction of alkanes with chlorine or bromine
alkanes react with chlorine to form a mixture of products with halogens substituting hydrogen atoms
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CH4+Cl2 makes
CH3Cl + HCl
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what is a free radical
its a reactive species which posses an unpaired electron
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what are the three steps on the mechanism of substitution
initiation,propagation,termination
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what happens in the initiation step
UV light breaks the Cl-Cl bond is broken the bond broken is the homolytic fission and each atom gets one electron
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what happens in propagation
chlorine free radicals very reactive and remove a H from the methane leaving a methyl radical group the methyl free radical then reacts with Cl to produce another product and another Cl2 free radical
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what is termination stage
two free radicals colliding could cause the chain to be terminated
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Card 2

Front

what is the process of fractional distillation

Back

oil is preheated,then passed into column,fractions condense at different heights,temperature column hottest at bottom, boiling point depends on size of molecules, small molecules condense at top larger at the bottom

Card 3

Front

what does the separation depend on in the fractioning column

Back

Preview of the front of card 3

Card 4

Front

what does vacuum distillation allow

Back

Preview of the front of card 4

Card 5

Front

what will lowering the pressure do over a liquid do to its boiling point

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