Organic Chemistry Flashcards
What is organic chemistry?
The chemistry of molecules based on carbon
Define an aromatic compound
Compound contains a benzene ring
Define an aliphatic coumpound
Compound does not contain a benzene ring
Define an alicyclic compound
Compound contains a ring but it is not a benzene ring
What does the term homologous series mean
A series of organic compounds having the same functional group with each successive member differing by CH2
What is the general formula for an alkane with n carbon atoms
CnH2n+2
Why does the alkane boiling point increase as you go down the group?
Chain length increases molecules have more electrons therfore there are stronger London forces between molecules which takes more energy to overcome
What happens if molecules have the same number of electrons?
The more branched molecule would have less surface area of contact so the boiling point would be lower
Why are alkanes not very reactive
Bonds are hard to break
Define nucleophiles
Lone pair donor
How can halogenoalkanes be converted to alcohols
Using aqueous sodium hydroxide and beating under reflex
Define refux
Continous boiling and condensation of a reaction mixture. Mixture will evaporate but condense in the condenser and fall back down into reaction vessel
Define hydrolysis
The breaking of a bond using water or aqueous alkali
What does the rate of a nucleopholic substation reaction depend on
The strength of the carbon halogen bond. C-I bond is weakest so most readily undergoes nucleophilic substitution
What are the limitations of using free radical substitution
-Multiple substitution occurs
-substitution occurs at different points along the chain making it hard to control which product is made
What is a free radical
A species with an unpaired electron
Describe the reactivity of radicals
Highly reactive as they want an extra electron
Define homolytic fission
The breaking of a bond where each atom in the bond receives 1 electron forming 2 radicals
What is the general formula for alkyl groups
CnH2n+1
Equation of an alkane being combusted with unlimited oxygen
Alkane+oxygen–>carbon dioxide +water
Equation of an alkane being combusted with limited oxygen
Alkane+oxygen–>carbon monoxide+water
Equation of alkane being combusted with very little oxygen
Alkane+oxygen–>carbon(soot) +water
How are sigma bonds formed?
The overlap of atomic orbitals directly between the bonded atoms
What are the steps for naming alkane?
1)find the longest chain of carbon stops. End of the name will be based on chain length
2) identify any side chains. They are put as prefixes to the main chain name(alkyl groups)
3)name the carbon atoms on the main chain from the side closest to the side chain
4)write out the name with side chains as prefixes. Put a number before the prefix to dhow which carbon it is attached to
Extra rules for naming alkanes
-prefixes go in alphabetical indeed
-put di/tri to show 2 or 3 of the same side chain
-dash between numbers and letters
-commas between numbers
What requirements are there for free radical substitution?
Ultraviolet light
Hydrolysis practical
1)dissolve haloalkane in ethanol
2) add aqueous AgNO3
3)AgX precipitate forms(X is the halide ion)
Colour will tell us which halide ion is present
What colour is AgCl
White
What colour is AgBr
Pale cream
What colour is AgI
Yellow
What can we use as an indicator of the rate of hydrolysis?
The rate of precipitate formation
What does the ozone do
It absorbs harmful ultraviolet radiation from the sun
What were chloroflurocarbons (CFC) used for?
Refrigerants and aerosols as propellants
How do CFCS make their way into the atmosphere?
Ultraviolet light breaks C-Cl bonds. C-F bonds do not break as they are too strong
What does the chlorine atom then do? (After c-cl bond breaks in cfc)
-Can cause the breakdown of ozone into oxygen
What can a single CFC molecule catalyse?
-the breakdown of up to 100,000 O3 molecules
What does ozone depletion allow?
Harmful UV to penetrate troposphere leading to increased incidence of skin cancer and genetic damage
