58-59/64-65 - Crude Oil and Hydrocarbons Flashcards
What are hydrocarbons?
Saturated fuels made only of carbon and hydrogen
What allows us to separate mixtures of hydrocarbons?
The different properties of the mixtures, as they are not chemically bonded
What are some properties of short molecule hydrocarbons?
Low melting point and boiling point (more volatile)
Gaseous
Not very viscous (gloopy)
More flammable
What are the first five alkanes?
Methane, ethane, propane, butane, pentane
Michel Eats Peanut Butter Poorly
Money Eats People’s Back Pockets
What is the formula for the structure of alkanes?
CnH(2n+2)
What is crude oil?
A mixture of hydrocarbons
What effects can crude oil have on the environment?
Oil spills damage habitats and organisms
Global warming
Acid rain
Global dimming
What can be done to reduce sulfur dioxide emissions?
Most of the sulfur can be removed from the fuels before they are burnt (this does require money and uses more energy)
Petrol and diesel can be rep,aced with low sulfur versions
Power stations now have acid gas scrubbers to remove harmful gases before they are released into the atmosphere
Fossil fuel usage could simply be reduced
What is cracking?
A thermal decomposition reaction that splits long-chain hydrocarbons
What does cracking produce?
A shorter alkane and an alkene
How do you crack a hydrocarbon?
- Heat it into a vapour
- Pass the vapour over a powdered catalyst
The molecules split apart on the surface of the catalyst
What are alkenes?
Unsaturated hydrocarbons (C=C double bond)
What are the first four alkenes?
Ethene
Propene
Butene
Pentene
What is the general formula for alkenes?
CnH2n - twice as many hydrogens as carbons
How can you test for an alkene?
By adding the substance to bromine water - a double bond will open up and form bonds with bromine, turning it from orange to colourless
How do you produce ethanol with ethene?
Hydrate it with steam in the presence of a catalyst
Why is producing ethanol with ethene not the only method?
Crude oil is non-renewable, so using ethene will become more expensive
If not with ethene, how is ethanol produced?
By fermentation
What can sugar be converted into? (Word equation)
Sugar -> carbon dioxide + ethanol
What are the advantages of producing ethanol from renewable resources?
Lower temperature required
Simpler equipment
Sugar is grown all over the world
What are the disadvantages of producing ethanol from renewable resources?
This ethanol is not very concentrated and must be distilled for strength
It needs to be purified
What are the steps of fractional distillation of crude oil?
Crude oil vapourised with heat
Different hydrocarbons condense at different temperatures
Leave the column through different tubes
What black substance is left after fuels are burned? Why?
Soot (carbon)
Incomplete combustion
