Topic 5 + 6 - Intro to organics + Halogenoalkanes Flashcards
What is a homologous series?
A series of molecules that show a gradual trend in physical properties, can be represented by a general formula and have the same functional group. Each successive member of the series differs by a CH2 group
Alkanes are saturated or unsaturated?
saturated
What is an isomer?
What are the 3 types?
Molecules with the same molecular formula but different structural formulae.
3 types:
Chain
Position
Functional
What is fractional distillation?
The continued evaporation and condensation of a reaction causing it separate due to differences in boiling points.
What is petroleum?
A complex mixture containing mainly alkane hydrocarbons that can be separated using fractional distillation.
Why do people using cracking?
To break up the less valuable (less in demand), longer chain hydrocarbons that are less flammable, into shorter chain alkanes and alkenes
What are the two types of cracking called?
Thermal and Catalytic
Describe thermal cracking and its benefits
High temp (up to 1000 degrees)
High pressure (up to 70 atm)
Produces lots of alkenes which can be used to make valuable polymers eg. poly(ethene)
Describe catalytic cracking and its benefits
Uses a zeolite catalyst at a slight pressure and high temp (450)
Mostly produces aromatic hydrocarbons and motor fuels
Using a catalyst cuts costs as it can be done at a lower pressure and temperature and it also speeds up the reaction which saves time.
Alkanes are useful for?
Fuels
Complete combustion of alkanes produces?
CO2 and H2O
What is produced/ can be produced in incomplete combustion?
Carbon Monoxide
Carbon dioxide
Carbon
How are oxides of nitrogen formed in the internal combustion engine?
Why is it bad?
High temperature and pressure inside car engines cause nitrogen and oxygen atoms in the air to react together.
Acid rain
How is the pollutant carbon formed in the internal combustion engine?
Why is it bad?
Incomplete combustion of hydrocarbons
Breathing problems and can also build up causing engine problems
How is the pollutant carbon monoxide formed in the internal combustion engine?
Why is it bad?
Incomplete combustion of hydrocarbons
Toxic to humans - limits RBCs capacity to carry oxgen
What is the issue with unburn hydrocarbons as a result of internal combustion engines?
React in the presence of sunlight to form ground level ozone (O3).
This irritates peoples eyes and is very bad for the respiratory system
How can (which) emissions be reduced using catalytic converters?
They reduce the output of carbon monoxide, nitrogen oxide and unburnt hydrocarbons.
Honeycomb shape (large surface area) made of ceramic material coated in platinum and rhodium (catalysts).
As the gases pass over this they react forming less harmful products. eg. co2 and nitrogen
How can we limit sulfur dioxide reaching the atmosphere in flue gases?
Calcium carbonate or calcium oxide is mixed with water to form an alkaline slurry.
The flue gases mix with the slurry and the acidic sulfur dioxide reacts with calcium compounds to form harmless salts.
Why is the ozone layer important?
Absorbs UV radiation which could be potentially harmful.
What are CFCs?
Chlorofluoroalkanes where all the hydrogens have been replaced by chlorine and fluorine atoms.
Why are CFCs bad?
Create holes in the ozone layer
How do CFCs create holes in the ozone layer?
Chlorine free radicals are forming in the ozone layer when C-Cl bonds are broken by UV radiation.
These free radicals are catalysts.
They attack the ozone in the atmosphere and regenerate more Cl free radicals.
It breaks down ozone into oxygen
What are the 2 equations and overall equation that show the decomposition of the ozone layer?
What is a nucleophile?
An electron pair doner?
Conditions for nucleophilic substitution of OH- CN-
Reflux reaction.
Alkane dissolved in ethanol
Aqueous sodium cyanide/hydroxide
Nucleophillic substitution using ammonia conditions?
Sealed container under pressure
Dissolve bromoethane in ethanol
Add concentrated NH3
Why do iodoalkanes react faster than fluoroalkanes?
As the C-I bond is shorter than C-F and therefore takes less energy to break.
Bond needs to break for the reaction to occur
What is a free radical?
A particle with an unpaired electron
What are the conditions for elimination reactions?
Alkaline and under reflux - dissolved in ethanol
Which solutions favour elimination and which conditions favour substitution?
Ethanolic solutions favour elimination
Aqueous solutions favour substitution
