alkanes Flashcards
general formula
CnH2n+2
alkanes
saturated hydrocarbons
what is petroleum
mixtures consisting mainly of alkanes hydrocarbons that can be separated by fractional distillation
what is crude oil
fossil fuel formed from the breakdown of remains that have been subjected to high pressure over millions of years made of alkenes
what does fractional distillation do
separate the crude oil into different fractions, fractions are a group of hydrocarbons that have similar boiling points and the crude oil is vaporised at the bottom of the column
how is is crude oil separated
there is a temperature gradient where it is hotter at the bottom and cooler at the top, the vapour will pass up the column and different fraction will condense at different heights so longer hydrocarbons will have a higher boiling point and will condense lower down
what is cracking
breaking the single bond in alkanes to produce shorter, more useful hydrocarbon chains
thermal cracking
takes place at high pressure and high temperature and produces a high percentage of alkanes
catalytic cracking
takes place at slight pressure, high temperature and in presence of zeolite catalyst and is used to produce motor fuels and aromatic hydrocarbons
what is complete combustion
burns with clear blue flame and water vapour and co2 is produced
what is incomplete combustion
alkene will burn with dirty yellow flame and can produce carbon, carbon monoxide and unburned hydrocarbons
what does the internal combustion of engine produce
pollutants and unburned hydrocarbons
what does combusting nitrogen containing alkanes do
form nitrogen oxide which contributes to acid Rain and photochemical smog, these gaseous pollutants
how can gaseous pollutants be prevented
using catalytic converters
what does combusting sulphur containing hydrocarbons do
lead to sulphuric dioxide that causes air pollution
