C7 Flashcards
Where do we find crude oil?
We find crude oil in rocks
Finite resource
How is crude oil formed?
Crude oil is formed over millions of years from the remains of plankton, which were buried in mud
What is crude oil?
Crude oil is a mixture of molecules called hydrocarbons
What is a hydrocarbon?
A molecule containing hydrogen and carbon only
What is the formula for Alkanes
C(n)H(2n)+2
Why are alkanes saturated molecules
Carbon is fully bonded to the hydrogen
How do we remember methane Ethane propane and butane?
My
Eggy
Poo
Burns
What are the properties of hydrocarbons
- viscosity increases as size of hydrocarbon increases
-flammability decreases as size of hydrocarbon increases
-boiling point increases as size of hydrocarbon increased
What happenes when hydrocarbon fuels combust
-Hydrocarbon fuels release energy when combusted
-carbon and hydrogen atoms react with oxygen and are oxidised
how do we separate hydrocarbons
fractional distillation
what happens in fractional distillation of crude oils?
-crude oil is heated to very high temperature
-crude oil vapour is fed into fractional distillation column
-column is hotter at bottom and cooler at top
-hydrocarbon vapours rise up the column
-hydrocarbons condense whn they reach bp
-liquid fractions are removed
-remaining hydrocarbons travel further up column
-they condense when they reach bp
what is removed from the bottom of the columb
very long chain hydrocarbons
what is removed from the top of the columb
very short hydrocarbon gases
what are fractions used for
-some fractions are used as fuels
-some fractions are used as feedstock(chemical used to make other chemicals)
what are fractions
fractions contain hydrocarbons with a similar number of carbon atoms
what happens during cracking
a long chain alkane is broken down(cracked) to produce smaller and more useful molecules
what is produced during the cracking of alkanes
shorter chain alkane
alkene
what are the conditions for catalytic cracking
in catalytic cracking we use high temperatures and a catalyst
what are the conditions for steam cracking
in steam cracking we use high temperatures and steam
what do alkenes contain
alkenes have double covalent bond between two carbon atoms
why are alkenes useful
-make polymers
-starting material for other chemicals
what is the difference between alkanes and alkenes
alkenes contain a double covalent bond
alkenes are more reactive then alkanes
how do we test for alkenes
-using bromine water(orange)
-if we shake the bromine water with our alkene it will turn colourless
