Hydrocarbons And Crude Oil Flashcards
What is organic chemistry
The chemistry of carbon compounds
General formula of alkanes
CnH2n+2
What is the general formula of alkenes
CnH2n
What is displayed formulae
The special arrangement of all the atoms and bonds in a molecule
What is molecular formulae
The actual number of each atom in a molecule one at a time eg C2H6
What is structural formulae
Similar to displayed formula not all bonds are shown although all atoms are still indicated using subscript numbers
What is a homologous series
a series of organic compounds that have similar features and chemical properties due to them having the same functional group.
First four alkenes
Methane Mice
Ethane Eat
Propane Paper
Butane Bags
What is a hydrocarbon
A compound made up of only carbon and hydrogen atoms
How is crude oil formed
Crude oil is formed over millions of years from the effects of high pressures and temperatures on the remains of biomass (plant and animals) mainly plankton that was buried in mud
What is a saturated hydrocarbon and give an example
A hydrocarbon with only single bonds between its atoms. This means that it contains as many hydrogen atoms as possible in each molecule eg an alkane
What is an unsaturated hydrocarbon and give a example
A hydrocarbon whose molecules contain at least one carbon-atom double bond eg. An alkene
Describe the process of fractional distillation
The crude oil is heated until vaporised, these vapours move up the fractioning column the further up the column the cooler it becomes. As the gasses move up the fractioning column they cool down, as each fraction condenses at a different temperature they are collected at different points, each fraction contains hydrocarbons with a similar number of carbon atoms. The refinery gasses have very low boiling points and do not condense and pass out the top of the fractioning column, longer chained hydrocarbons such as bitumen have higher boiling points and collected towards the bottom of the column whereas shorter chained hydrocarbons like petrol are collected near the top.
Give 5 examples of products obtained from crude oil
Polymers, lubricants, Solvents, detergents and adhesives
What is liquified petroleum gas used for
Domestic heating & cooking
What is petrol used for
Fuel for cars
What is kerosene for
Jet fuel
What is diesel for
Powering diesel engines
what is heavy fuel oil for
Ships & power stations
What is bitumen used for
Surfacing roads and roofs
What is the order of fractions in the column ascending
Bitumen, fuel oil, diesel, kerosene (paraffin), petrol (gasoline) , refinery gases
How does boiling point correspond with the size of their molecules
the intermolecular forces of attraction between large molecules becomes greater as there are more electrons in the molecules and greater surface area contact between them meaning that more heat is needed to separate the molecules, hence with increasing molecular size there is an increase in boiling point
What is viscosity
The ease of flow of a liquid, high viscosity liquids are thick and flow less easily
How does viscosity correspond to chain length
Viscosity increases with increasing chain length, due to the increased intermolecular forces of attraction as molecular size increases
How does flammability correspond to chain length
smaller hydrocarbon molecules are more flammable and are easier to ignite than larger molecules
Equation for complete combustion
Hydrocarbons + oxygen —> carbon dioxide+ water
Equation for incomplete combustion
Hydrocarbon + oxygen —> carbon monoxide + carbon + water
Equation for incomplete combustion when there is not enough oxygen to form monoxide
Hydrocarbon + oxygen —> carbon + water
What are the 2 methods used for cracking alkanes
Catalytic cracking and steam cracking
Describe the process for cracking
The hydrocarbon is heated until vapourised/ evaporated, the broken porcelain or aluminium oxide acts as a catalyst, as the vapours pass over the catalyst thermal decomposition occurs and hydrocarbon is cracked into smaller chained hydrocarbons and an alkane and an alkene are produced
Why are alkenes more desirable than alkanes
They are more reactive because due to the presence of carbon carbon double bond so they can take part in reactions alkanes can’t
What 2 useful reactions do alkenes undergo
Bromination and polymerisation
What is the test for alkanes/alkenes
Bromine water
Alkane + bromine water=no reaction & solution stays orange
Alkene + bromine water=reaction & solution turns colourless
