3.3.2 Alkanes Flashcards
What are alkanes?
Saturated hydrocarbons
What is petroleum?
A mixture consisting mainly of alkane hydrocarbons
How are the components of petroleum separated?
Fractional distillation
What is cracking?
The process that involves breaking C-C bonds in alkanes
What is thermal cracking? (3)
High temperature (1000°C) High pressure (70 atm) Produces a high percentage of alkenes
What is catalytic cracking? (4)
Slight pressure
High temperature (500°C)
Zeolite catalyst (hydrated aluminosilicate)
Produces aromatic hydrocarbons and alkanes for motor fuels
What is the economic reason for cracking alkanes?
There is a higher demand for lighter fractions so they are more valuable
What are alkanes used for?
Fuel
Which pollutants are produced in internal combustion engines? (4)
Oxides of nitrogen
Carbon monoxide
Carbon
Unturned hydrocarbons
Car engine pollutants - nitrogen oxides (4)
Toxic and poisonous
NO produced in high temperature and pressure in engine from nitrogen and oxygen in the air
Nitrogen dioxide produced when nitrogen monoxide reacts further with oxygen
React with unturned hydrocarbons to form ground-level ozone (smog) - irritates eyes, respiratory systems, lungs
How do catalytic converters remove pollutants from exhaust? (2)
2NO > N2 + O2
2NO + 2CO > N2 + 2CO2
How is sulphur dioxide produced from fuels?
Combustion of hydrocarbons containing sulphur
Car engine pollutants - sulphur dioxide (3)
Dissolves in moisture in the air to form acid rain
Removed from flue gases using alkaline slurry as sulphur dioxide is acidic so a salt is formed
CaO + SO2 > CaSO3
How does methane react with chlorine? (3)
Free radical substitution
Requires UV light
Initiation, propagation, termination
