Alkanes Flashcards
what are alkanes
saturated hydrocarbon homologous series with general formula C2n H2n+2
what is petroleum
a mixture consisting mainly of alkane hydrocarbons that can be separated by fractional distillation
what is cracking and what does it involve
involves breaking c-c bonds in alkanes
long chain hydrocarbons that are in high supply and low demand can be cracked into shorter chain hydrocarbon
what is thermal cracking and what are the conditions
thermal cracking takes place at high pressure and high temperature and produces a high percentage of alkanes
temp - 900*c
pressure - 70atm
catalyst - none
products - alkenes
what is catalytic cracking and what are the conditions
Catalytic cracking takes place at a slight pressure, high temperature and in the presence of a zeolite catalyst and is used mainly to produce motor fuels and aromatic hydrocarbons
temp - 450*c
pressure - 1-2atm
catalyst - zeolites
products - motor fuels
what are alkanes used as
fuels
what are the types of combustion
complete - with excess oxygen
incomplete - with limiting oxygen
what is produced from internal combustion engine
number of pollutants including NOx CO and unburned hydrocarbons
how can you remove gaseous pollutants from internal combustion engine
use a catalytic converter
key phrase for catalytic converter
converters have a honey comb coated with a thin layer of catalytic platinum to give a large surface area. this boosts efficiency and lowers the cost of the catalytic converter by reducing the amount of catalyst needed
what causes acid rain
Sulfur impurities when burned can release SO2 it can cause respiratory problems as well as acid rain
S+O2-> SO2
SO2 will dissolve in atmospheric water and can produce acid rain
how can catalytic converters prevent acid rain
SO2 can be removed from the emissions by flue gas desulfurisation. this is where the gas is passed through calcium oxide solution which reacts with SO2 and creates aqueous salt.
