Seneca 7.1 Flashcards
What type of resource is crude oil
Non - renewable (finite)
Where is crude oil found
Crude oil is found in rocks and is used to produce fuels and other important chemicals.
What is crude oil made from
Crude oil is made from the fossilised remnants of ancient plankton.
What makes up crude oil
Crude oil is a mixture of lots of different compounds that are not chemically combined.
Most of the compounds in crude oil are hydrocarbons.
What are hydrocarbons
Hydrocarbons are molecules made up of only hydrogen and carbon atoms.
Hydrocarbons differ in their size, which can change the properties of the hydrocarbon.
What are the properties of long chain hydrocarbons
. Higher boiling points
. Higher viscosity
. Less flammable
What are two uses of crude oil
. Tarmac
. Fuels
What is the structure of alkanes
In alkanes, carbon atoms bond to four atoms (hydrogen or carbon).
We call them saturated hydrocarbons as all their bonds with other atoms are single bonds.
What are the uses of alkanes
Alkanes have quite low reactivity, but they combust quite well.
This makes them useful as fuels.
What is the formula for alkanes
Alkanes have the general formula CnH(2n+2
What are the 4 smallest alkanes in ascending order
Methane (CH4)
Ethane (C2H6)
Propane (C3H8)
Butane (C4H10)
What is fractional distillation
Fractional distillation is the process of separating crude oil into groups of hydrocarbons with similar numbers of carbon atoms. We call these groups of hydrocarbons “fractions”.
Short - chain hydrocarbons
Hydrocarbons with few carbon atoms are called ‘short-chain hydrocarbons’.
Long - chain hydrocarbons
Hydrocarbons with lots of carbon atoms are called ‘long-chain hydrocarbons’.
What are the steps of fractional distillation
Evaporation
Condensation
Collection
Fractional distillation - Evaporation
We evaporate the crude oil by heating it.
Crude oil vapor is put into a fractionating column at the bottom and rises upwards.
Fractional distillation - Condensation
The temperature is highest at the bottom of the column. Long-chain hydrocarbons condense at the bottom and are collected as liquids.
Short-chain hydrocarbons have lower boiling points. They pass up the column and condense at lower temperatures nearer the top.
Fractional distillation - Collection
The fractions are collected. They are then processed to create end products:
Fuels (e.g. petrol, diesel) are a common end product.
The petrochemical industry can use some fractions as feedstock (material used in an industrial process) to make products such as solvents, detergents, lubricants etc.
What are organic compounds
Carbon - containing compounds
What are homologous series
A family of similar compounds
What happens if we burn hydrocarbons with a lack of oxygen
If alkanes are burned without enough oxygen, then carbon monoxide can be created:
2C + O2 → 2CO
What are the properties of carbon monoxide
. Colorless
. Toxic
. Odorless
What happens if we burn hydrocarbons with plenty of oxygen
The combustion (burning) of hydrocarbons when there is a good air supply involves:
The release of energy.
The oxidation of carbon and hydrogen to create carbon dioxide and water.
Why do heavy fractions of crude oil not make good fuels
Because they :
. Have high boiling points
. Have low volatility
. Don’t ignite easily
What is cracking
Cracking is the process that breaks down long-chain hydrocarbons into shorter-chain molecules that are more useful
What is cracking an example of
Cracking is an example of a thermal decomposition reaction
What are the two methods of cracking
. Steam cracking
. Catalytic cracking
Steam cracking
Vaporized heavy hydrocarbons are combined with steam in a high temperature environment.
Alkanes and alkenes are produced by this reaction.
E.g. decane → octane + ethene
Catalytic cracking
Vapourised heavy hydrocarbons are passed over the top of a heated catalyst.
Alkanes and alkenes are produced by this reaction.
E.g. hexane → butane + ethene
What are the products of cracking
Alkane
Alkene
What are the uses of alkenes
. Starting materials for many chemicals
. Being combined to make polymers
