c9 Flashcards
what is crude oil
a finite resource found in rocks and is a mixture of many different compounds that boil at different temperatures
what is the crude oil mixture separated for
to make useful fuels
how can you separate a mixture of liquids
distillation
what are the most the compounds found in crude oil
hydrocarbons
what are the hydrocarbons in crude oil
alkanes that are saturated hydrocarbons
what is the mnemonic for the first 4 hydrocarbons
monkeys eat peeled bananas
how is crude oil separated
fractional distillation
what does the larger the molecule mean to a hydrocarbon
the larger the molecule, the higher the boiling point
how does fractional distillation work
-the crude oil is vaporised and fed into a fractioning column
-inside the column there are many trays with holes to allow gases through.
-the hydrocarbons condense to liquids when they reach their level that is at their boiling point.
-different liquids collect on the trays at different levels.
how does a fractionating column work
a tall tower that is hot at the bottom snd cool at the top
what does a low viscosity mean
they are runny liquids
what do fractions with a smaller molecule have
have lower boiling points, low viscosity and are very flammable.
what does burning any fuel produce
carbon dioxide
what happens when pure hydrocarbons are burnt completely
they are oxidised to carbon dioxide and water
how do you test for water
blue cobalt chloride paper which will turn pink in contact with water
how can large hydrocarbons be broken down into smaller molecules
cracking
how can cracking be done
steam cracking - by heating a mixture of hydrocarbon vapours and steam to a very high temperature
or
catalytic cracking - by passing hydrocarbon vapours over a hot catalyst
what are the two methods of cracking
steam and catalytic
what happens during cracking
thermal decomposition reactions produce a mixture of smaller molecules which some are alkanes and some alkenes
what are alkenes
unsaturated hydrocarbons because they contain fewer hydrogen atoms..
how do you know if the molecule is unsaturated
double covalent bond between carbon atoms
what makes alkenes more reactive than alkanes
alkenes have a double carbon bond
how can you test for unsaturated compounds
bromine water which will turn from orange to colourless if there is unsaturated compounds
what is a fraction
liquids with different boiling ranges separated from a mixture of liquids