3.3 - Organic Intro, Alkanes & Haloalkanes Flashcards
What is structural isomerism?
molecules with same molecular formula but different structure
What is stereoisomers?
molecules with same structural formula but atoms have different spatial arrangement
Which catalyst Is used in the catalytic cracking of alkanes
Zeolite
Why do E-Z isomers form?
Because there is restricted rotation around the C=C double bond
Describe thermal cracking
- high temperature & pressure
- produces a high % of alkenes
Describe catalytic cracking
- slight pressure
- high temperature
- in the presence of a zeolite catalyst (larger SA)
- used mainly to produce motor fuels & aromatic hydrocarbons
What are economic reasons for cracking alkanes
- fractions with shorter C chains are in more demand than larger fractions
- longer hydrocarbons are cracked into smaller more useful ones
- the products of cracking are more valuable
What is incomplete combustion & what products are formed (alkanes)
Combustion in a limited supply of O2
CO - carbon monoxide (poisonous)
soot (global dimming)
What type of hydrocarbons are most likely to undergo incomplete combustible
Longer chains
What do catalytic converters catalyse (equations)
2CO(g) + 2NO (g) —> N2 (g) + 2CO2 (g)
hydrocarbons + NO —> N2 + CO2 + H20
What is the ozone layers function?
To protect the Earth from harmful exposure to too many UV rays
How do CFCs break the ozone layer down? 
Free radical substitution 
What’s the difference between nucleophilic substitution and elimination ( both have OH)
NS: OH acts as a nucleophile
Elimination: OH acts as a base (proton accepter) + makes water
How is ozone beneficial
It absorbs harmful UV radiation
How are chlorine atoms formed in the upper atmosphere
When UV radiation causes C-Cl bonds in CFCs to break
What contributes to ozone layer depletion
Chlorine atoms catalyse the decomposition of ozone and contribute to the hole in the ozone layer
What is a nuclophile?
An electron pair donor
What is an electrophile?
An electron pair acceptor
Explain why a very thin layer of metals are used in catalytic converter
- to reduce amount of metals needed
- increase surface area
What is a racemic mixture ?
A mixture of equal amounts of enantiomers
What is the danger of using KCN?
It is water reactive and can produce HCN gas which is toxic and flammable
Describe optical isomerism
- a type of stereoisomerism
- chiral = cannot be superimposed on eachother
Explain how oxides of nitrogen are formed in engines
Reaction of nitrogen and oxygen from the air at high temperatures
Why are oxides of nitrogen emissions from vehicles bad?
Formation of acid rain
Why are carbon particulates formed in vehicles
Incomplete combustion
Why do you always show the major product in mechanisms?
The secondary carbocation is more stable than the primary due to the inductive effect of more alkyl groups
Why is a racemic mixture produced
- planar carbonyl group
- can be attacked from either side with equal probability
- produces equal amounts of the two isomers
Why can sulfur dioxide be removed from flue gases using calcium oxide or carbonate
By flue gas desulfurisaration:
- the basic calcium oxide reacts with the acidic sulfur dioxide in a neutralisation reaction
How does carbon-halogen bond enthalpy influence ROR
The weaker the bond the easier to break so the faster the reaction
How do you draw a position isomer
Just draw the functional group on a different carbon
How do you draw a functional group isomer
Change the functional group into a different one eg move the O in a alcohol to the middle so its not a alcohol anymore
How do you draw a chain isomer
Change the structure of the main carbon chain eg use branching of methyl groups
Why does carbon dioxide absorb infrared radiation?
The C=O bonds vibrate the same frequency as IR
How does carbon dioxide cause global warming?
- C=O bonds absorb infrared radiation
- IR radiation emitted by the Earth does not escape
What’s the general formula of a alkane
2n + 2
What is a free radical
A reactive species which possesses an unpaired electron
