Hydrocarbons: Fuel & Feedstock (AQA GCSE Chemistry)
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What is crude oil made up of?
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What is crude oil made up of?
Crude oil is made up of a mixture of a large number of compounds including hydrocarbons.
Define the term hydrocarbon.
Hydrocarbons are compounds that are made up of carbon and hydrogen only.
True of False?
Crude oil is a renewable resource found in rocks.
False.
Crude oil is a finite resource found in rocks.
Crude oil is the remains of an ancient biomass consisting mainly of .................. that was buried in mud.
Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud.
What is the general formula of an alkane?
The general formula of an alkane is CnH2n+2.
What is the name and molecular formula of the alkane containing one carbon atom?
The name and molecular formula of the alkane containing one carbon atom is methane and CH4.
What is the name and molecular formula of the alkane containing two carbon atoms?
The name and molecular formula of the alkane containing two carbon atom is ethane and C2H6.
What is the name and molecular formula of the alkane containing three carbon atoms?
The name and molecular formula of the alkane containing three carbon atom is propane and C3H8.
What is the name and molecular formula of the fourth alkane?
The fourth alkane is butane, with the molecular formula C4H10.
What is the name of the following alkane?
The name of the following alkane is butane.
What is the name of the following alkane?
The name of the following alkane is ethane.
What does a displayed formula show?
A displayed formula shows the spatial arrangement of all the atoms and bonds in a molecule.
What does a general formula show?
A general formula tells you the composition of any member of a whole homologous series of organic compound.
Define structural formulae.
Structural formulae show enough information to make the structure clear, but most of the actual covalent bonds are omitted.
Only important bonds like double and triple bonds are always shown.
What is a molecular formula?
A molecular formula is the actual number of atoms of each element in a compound.
What is the displayed formula of propane, C3H8?
The displayed formula of propane is:
True or False?
Each fraction in crude oil consists of groups of hydrocarbons with similar chain lengths.
True.
Each fraction in crude oil consists of groups of hydrocarbons with similar chain lengths.
Define fractional distillation.
Fractional distillation is the process of separating the different fractions of crude oil based on their boiling points.
True or False?
The size and length of each hydrocarbon molecule determines which fraction it will be separated into.
True.
The size and length of each hydrocarbon molecule determines which fraction it will be separated into.
True or False?
As you move up a fractionating column, the temperature increases.
False.
As you move up a fractionating column, the temperature decreases.
What is the use of liquefied petroleum gas?
Liquefied petroleum gas is used for domestic heating & cooking.
True or False?
Kerosene is used as jet fuel.
True.
Kerosene is used as jet fuel (paraffin).
What is diesel used for?
Diesel is used in diesel engines (gas oil).
Give a use of heavy fuel oil.
Heavy fuel oil is used for ships & power stations.
Why do fractions condense inside the fractionating column?
Fractions condense inside the fractionation tower because their vapours rise and reach a point where the temperature is below their boiling point.
What is petrol used for?
Petrol is used as fuels for cars.
True or False?
The vapours of hydrocarbons with high boiling points condense at the top of the column.
False.
The vapours of hydrocarbons with high boiling points condense at the bottom of the column.
Why does the boiling point of a molecule increase as the molecule becomes larger?
As the molecules get larger, the intermolecular forces of attraction become greater so more energy is needed to overcome them.
Define the term viscosity.
Viscosity is the ease of flow of a liquid.
What happens to the viscosity of a hydrocarbon liquid as the molecular size increases?
As the molecular size increases, the viscosity of a hydrocarbon liquid increases.
What are the products of complete combustion of hydrocarbons?
The products of complete combustion of hydrocarbons are carbon dioxide and water.
What is the symbol equation for the complete combustion of propane, C3H8?
The symbol equation for the complete combustion of propane is:
C3H8 + 5O2 → 3CO2 + 4H2O
True or False?
Larger hydrocarbon molecules are more flammable and are easier to ignite than smaller molecules.
False.
Smaller hydrocarbon molecules are more flammable and are easier to ignite than larger molecules
How does the flammability of alkanes change as they increase in size?
Flammability decreases as alkanes increase in size.
Are long or short chain alkanes better to use as fuels?
Short chain alkanes better to use as fuels.
Why are long chain alkanes useful as lubricants in machinery?
Long chain alkanes are useful as lubricants in machinery as they are more viscous.
True or False?
High viscosity liquids are thick and flow less easily.
True.
High viscosity liquids are thick and flow less easily.
What is the purpose of cracking?
The purpose of cracking is to convert surplus unwanted fractions of crude oil, such as kerosene and diesel oil, into more useful fractions like petrol (gasoline), alkenes, and hydrogen which are in high demand.
True or False?
The demand for certain fractions outstrips the supply, which is why cracking is necessary.
True.
The demand for certain fractions outstrips the supply, which is why cracking is necessary to convert surplus unwanted fractions into more useful ones.
What are the two methods used for cracking alkanes?
The two methods used for cracking alkanes are:
Catalytic cracking
Steam cracking
True or False?
Cracking is an exothermic reaction.
False.
Cracking is an endothermic reaction.
Complete the equation for the cracking of decane to produce ethene and an alkane.
C10H22 → ............ + C2H4
The equation for the cracking of decane to produce ethene and an alkane is:
C10H22 → C8H18 + C2H4
True or False?
Alkanes are saturated compounds, and alkenes are unsaturated compounds.
True.
Alkanes are saturated compounds, and alkenes are unsaturated compounds.
Name the catalyst used in catalytic cracking.
The catalyst used in catalytic cracking is:
Alumina / aluminium oxide / Al2O3
ORSilica / silicon dioxide / SiO2
True or False?
Cracking is a type of substitution reaction.
False:
Cracking is a type of thermal decomposition reaction.
True or False?
Long chain fractions are in high supply but in low demand.
True.
Long chain fractions are in high supply but in low demand.
This explains why they are cracked into more useful, shorter chain alkanes and alkenes.
State one use for the short chain alkenes formed in cracking.
Uses for the short chain alkenes formed in cracking include:
Making polymers / plastics
Making ethanol
What is formed when a long chain hydrocarbon undergoes cracking?
A long chain hydrocarbon is cracked to form shorter chain alkanes and shorter chain alkenes.
What chemical is used to test for the presence of a C=C bond?
Bromine water is used to test for the presence of a C=C bond.
What is the colour change when bromine water is added to an alkene?
The colour change when bromine water is added to an alkene is orange to colourless.
True or False?
Alkenes are used to make polymers and are the starting materials for the production of many other chemicals.
True.
Alkenes are used to make polymers and are the starting materials for the production of many other chemicals.
