year 1 organic chem Flashcards

1
Q

what are isomers

A

molecules that have the same molecular formula but their atoms are arranged differently

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2
Q

what are structural isomers

A

molecules that have the same molecular formula but a different structural formula

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3
Q

what are the different types of structural isomer

A

-chain (different carbon chain)
-position (functional group in different position)
-functional group (different functional group)

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4
Q

what are stereoisomers

A

-same molecular and structural formula but a different arrangement of atoms in space

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5
Q

how do stereoisomers arise

A

restricted rotation around C=C double bond
each carbon in double bonds has 2 different groups attached

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6
Q

give every step of FRS of C2H6 to make C2H5Cl

A

intitiation: Cl2 –> 2Cl*
propagation 1: C2H6 + Cl* –> C2H5* + HCl
propagation 2: C2H5* + Cl2 –> C2H5Cl + Cl*
termination: C2H5* + Cl* –> C2H5Cl
overall: C2H6 + Cl2 –> C2H5Cl + HCl

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7
Q

how is ozone formed

A

O2 –> 2O (by UV radiation)
O + O2 –> O3

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8
Q

how is ozone depleted

A

O3 –> O2 + O (by UV radiation)

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9
Q

what are CFCs

A

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

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10
Q

what are the propagation reactions in the depletion of ozone and what is the role of Cl*

A

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

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11
Q

what is a nucleophile

A

an electron pair donor

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12
Q

why do nucleophilic substitution reactions happen to haloalkanes

A

-difference in electronegativity between C-X(halogen)
-C is slightly positive
-electron pair on nuclephile attracted to C

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13
Q

what are the reactants and conditions in nucleophilic substitution

A

alcohol- KOH, aqueous
nitrile- KCN, aqueous alcoholic
amine- NH3, XS

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14
Q

evaluate fermentation as a method to produce alcohols

A

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

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15
Q

evaluate hydration of alkenes as a method to produce alcohols

A

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

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16
Q

what is a biofuel

A

a fuel made from biological material that has recently died

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17
Q

advantages and disadvantages of biofuel

A

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

18
Q

equations that suggest biofuel is carbon neutral

A

photosynthesis:
6CO2 + 6H2O –> C6H12O6 + 6O2
production of ethanol:
C6H12O6 –> 2C2H5OH + 2CO2
combustion of ethanol:
2C2H5OH + 6O2 –> 4CO2 + 6H2O

19
Q

why might biofuel not be carbon neutral

A

fossil fuels need to be burnt for machinery to harvest the crops, refine and transport the bioethanol which produces CO2.

20
Q

what is an electrophile

A

an electron pair acceptor

21
Q

what is the major product in electrophilic addition

A

tertiary carbocations- more alkyl groups which are electron pushing- more stable

22
Q

what are addition polymers

A

-made from alkenes
-double bond opens up and monomers join together to form on long saturated chain
-exothermic reaction

23
Q

properties of addition polymers

A

-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

24
Q

how to maximise yield of product in distillation

A

-cool receiving flask
-don’t let temp get high than b.p of product

25
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
26
oxidation of alchols
primary--> aldehydes (distillation, acidified K2Cr2O7) primary--> carboxylic acid (reflux, XS acidified K2Cr2O7) secondary--> ketones (reflux, acidified K2Cr2O7)
27
conditions for elimination of alcohols
conc H2SO4 catalyst reflux
28
conditions for elimination of haloalkanes
KOH, ethanolic
29
test for alkenes
orange bromine water turns colorless
30
test for carboxylic acids
add sodium hydrogen carbonate CO2 effervescence produced that can be tested by limewater
31
test for alcohols
primary and secondary alcohols turn orange acidified potassium dichromate green
32
test for aldehydes
tollen's reagent forms silver mirror
33
test for haloalkanes
nitric acid sliver nitrate
34
what is the molecular ion peak in mass spec
clear peak with largest m/z ratio (furthest right) indicates molecular mass of molecule
35
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
36
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
37
describe thermal cracking
-high temp and high pressure -produces a lot of alkenes -alkenes used to make polymer
38
describe catalytic cracking
-zeolite catalyst -slight pressure and high temperature -mainly produces aromatic hydrocarbons
39
why is carbon monoxide bad
poisonous as it binds to haemoglobin rather than oxygen can be removed from exhaust gases by catalytic converters
40
why is carbon bad
-soot causes respiratory problems -can build up in engines causing them not to work properly
41
why are oxides of nitrogen bad
causes respiratory problemss
42
why is SO2 bad
causes acid rain, killing vegetation, fish and corroding buildings