Crude Oil Flashcards
Crude oil is derived from what?
Ancient biomass found in rocks.
True or false…crude oil is a mixture of a small number of compounds.
False. Crude oil is a mixture of a very large number of compounds.
A mixture consists of…
…two or more compounds not chemically bonded together.
It is possible to separate a mixture such as crude oil by what method?
Fractional distillation.
Most of the compounds found in crude oil are what?
Hydrocarbons.
What is a hydrocarbon?
A compound made only of hydrogen and carbon atoms.
Most hydrocarbons in crude oil are saturated…
…alkanes, which have the general formula CnH2n+2.
Fractional distillation is the process of…
…evaporating crude oil into fractions of similarly lengthen molecules in a column. At different temperatures the crude oil condenses at different lengths up the column where it is collected.
Properties of hydrocarbons may depend upon their…
…length (number of carbon atoms).
Fractions are…
…mixtures of hydrocarbons with a similar number of carbon atoms. This is because they have similar boiling/melting points.
A larger hydrocarbon has what properties?
Higher boiling points.
More viscous.
Less volatile.
Less flammable.
During combustion of a hydrocarbon, energy is released. Hydrogen and carbon become…
…oxidised.
Environmental problems with hydrocarbons combusting.
Sulphur dioxide and oxides of nitrogen cause acid rain, carbon dioxide is a greenhouse gas and causes global warming, whilst solid particles cause global dimming.
How can acid rain be prevented during the combustion of hydrocarbons?
Sulphur can be removed before the fuels are burnt and sulphur dioxide can be removed from waste gases after combustion (eg: in power stations).
An alternative fuel to hydrocarbons?
Biofuels (eg: biodiesel and ethanol).
Hydrocarbons can be made smaller by what method?
Cracking.
How does cracking work?
Hydrocarbons are vaporised and passed over a catalyst where thermal decomposition takes place.
What are the products of cracking?
Alkanes and smaller unsaturated hydrocarbons called alkenes.
What is the general formula for alkenes?
CnH2n
What test can be done to see if an unsaturated alkene is present?
Mix with bromine water. If alkenes are present it will turn form orange to colourless.
Alkenes can be joined to make what type of materials?
Polymers.
What is a polymer?
A chain of monomers (single molecules). Eg: Ethene can be used to make polyethene.
Uses of polymers.
Food packaging, waterproofs, wound dressings, dental polymers, smart materials (including shape memory foams).
How are plastic bags being made biodegradable?
They are being made of polymers and cornstarch so that the break down more easily.
How can ethanol be made?
1)Hydration of ethene with steam over a catalyst.
or
2)Fermentation with yeast:
Sugar = carbon dioxide + ethanol
