year 1 organic chem Flashcards
what are isomers
molecules that have the same molecular formula but their atoms are arranged differently
what are structural isomers
molecules that have the same molecular formula but a different structural formula
what are the different types of structural isomer
-chain (different carbon chain)
-position (functional group in different position)
-functional group (different functional group)
what are stereoisomers
-same molecular and structural formula but a different arrangement of atoms in space
how do stereoisomers arise
restricted rotation around C=C double bond
each carbon in double bonds has 2 different groups attached
give every step of FRS of C2H6 to make C2H5Cl
intitiation: Cl2 –> 2Cl*
propagation 1: C2H6 + Cl* –> C2H5* + HCl
propagation 2: C2H5* + Cl2 –> C2H5Cl + Cl*
termination: C2H5* + Cl* –> C2H5Cl
overall: C2H6 + Cl2 –> C2H5Cl + HCl
how is ozone formed
O2 –> 2O (by UV radiation)
O + O2 –> O3
how is ozone depleted
O3 –> O2 + O (by UV radiation)
what are CFCs
non-flammable, unreactive compounds that contain carbon, fluorine and chlorine
diffuse into stratosphere where UV light proves energy to break C-Cl bond, forming Cl* radicals
what are the propagation reactions in the depletion of ozone and what is the role of Cl*
O3 + Cl* –> O2 + ClO
O3 + ClO –> 2O2 + Cl
overall: 2O3 –> 3O2
Cl has acted as a catalyst as it is regenerated and doesn’t appear in the overall equation
what is a nucleophile
an electron pair donor
why do nucleophilic substitution reactions happen to haloalkanes
-difference in electronegativity between C-X(halogen)
-C is slightly positive
-electron pair on nuclephile attracted to C
what are the reactants and conditions in nucleophilic substitution
alcohol- KOH, aqueous
nitrile- KCN, aqueous alcoholic
amine- NH3, XS
evaluate fermentation as a method to produce alcohols
C6H12O6 –> 2C2H5OH + 2CO2 (exothermic)
glucose from sugar cane is fermented with yeast under anaerobic conditions, producing ethanol and CO2
optimum temp for enzymes in yeast 50-60 degrees
adv: cheap equipment, renewable resources
disadv: batch process-slow, ethanol needs to be purified by fractional distillation- time and money
evaluate hydration of alkenes as a method to produce alcohols
C2H4 + H2O –> C2H5OH
steam and H3PO4 catalyst
adv- continuous process- fast
-no waste products - 100% atom economy
disadv- non-renewable resource
-high temp, lots of energy used - expensive
what is a biofuel
a fuel made from biological material that has recently died
advantages and disadvantages of biofuel
adv- made from renewable resources- more sustainable
usually classed as carbon neutral
disadv- petrol engines would have to be modified to store fuel with such a high ethanol conc
growing crops for biofuel takes up large areas of land
equations that suggest biofuel is carbon neutral
photosynthesis:
6CO2 + 6H2O –> C6H12O6 + 6O2
production of ethanol:
C6H12O6 –> 2C2H5OH + 2CO2
combustion of ethanol:
2C2H5OH + 6O2 –> 4CO2 + 6H2O
why might biofuel not be carbon neutral
fossil fuels need to be burnt for machinery to harvest the crops, refine and transport the bioethanol which produces CO2.
what is an electrophile
an electron pair acceptor
what is the major product in electrophilic addition
tertiary carbocations- more alkyl groups which are electron pushing- more stable
what are addition polymers
-made from alkenes
-double bond opens up and monomers join together to form on long saturated chain
-exothermic reaction
properties of addition polymers
-non polar, insoluble in water and generally unreactive (non-biodegradable)
-used as insulation/packaging
-only VDW
-longer chains = stronger VDW
-plasticisers make polymers more flexible
how to maximise yield of product in distillation
-cool receiving flask
-don’t let temp get high than b.p of product
precautions when refluxing
-don’t seal end of container as build up of gas increases pressure and apparatus may explode
-anti-bumping granules make small bubbles form rather than large
oxidation of alchols
primary–> aldehydes (distillation, acidified K2Cr2O7)
primary–> carboxylic acid (reflux, XS acidified K2Cr2O7)
secondary–> ketones (reflux, acidified K2Cr2O7)
conditions for elimination of alcohols
conc H2SO4 catalyst
reflux
conditions for elimination of haloalkanes
KOH, ethanolic
test for alkenes
orange bromine water turns colorless
test for carboxylic acids
add sodium hydrogen carbonate
CO2 effervescence produced that can be tested by limewater
test for alcohols
primary and secondary alcohols turn orange acidified potassium dichromate green
test for aldehydes
tollen’s reagent forms silver mirror
test for haloalkanes
nitric acid
sliver nitrate
what is the molecular ion peak in mass spec
clear peak with largest m/z ratio (furthest right)
indicates molecular mass of molecule
describe fractional distillation of crude oil
-crude oil is vaporised
-fed into fractionating column
-largest hydrocarbons don’t vaporise. they form residue at the bottom
-fractionating column is cooler at the top
-different chain lengths have different boiling points and condense at different temperatures at different levels of the column
-hydrocarbons with the lowest boiling points don’t condense and are drawn off as gases from the top
what is each fraction used for
-LPG gas - camping gas
-petrol
-kerosene - jet fuel, central heating fuel
-gas oil - diesel fuel
-fuel oil - ships, power stations
-bitumen - road surfacing
describe thermal cracking
-high temp and high pressure
-produces a lot of alkenes
-alkenes used to make polymer
describe catalytic cracking
-zeolite catalyst
-slight pressure and high temperature
-mainly produces aromatic hydrocarbons
why is carbon monoxide bad
poisonous as it binds to haemoglobin rather than oxygen
can be removed from exhaust gases by catalytic converters
why is carbon bad
-soot causes respiratory problems
-can build up in engines causing them not to work properly
why are oxides of nitrogen bad
causes respiratory problemss
why is SO2 bad
causes acid rain, killing vegetation, fish and corroding buildings
