A hydrocarbon is a molecule containing only hydrogen and carbon
Show the empirical formulae, molecular formulae, general formulae, structural formulae and displayed formulae of butane
Show the empirical formulae, molecular formulae, general formulae, structural formulae and displayed formulae of ethane
What is a general formula?
A formula to show the relative quantity of different types of atom for a molecules in a homologous series. Eg CnH2n+2 for alkanes
Explain the term functional group
A functional group is an atom or a group of atoms that determine the chemical properties of a compound
Explain the term homologous series
A homologous series is a family of compounds with 1) the same general formula 2) similar chemical properties 3) trends in their physical properties
What are isomers?
Molecules with the same molecular formula but with a different structure
Write all the possible different structural and displayed formulae of C₄H₁₀
Write all the possible different structural and displayed formulae of C₄H₈
Write all the possible different structural and displayed formulae of C₅H₁₂
In what type of reaction is an atom or group of atoms added to a molecule without taking anything away?
In what type of reaction is an atom or group of atoms replaced by a different atom or group of atoms?
What is a substitution reaction?
A reaction where an atom or group of atoms is replaced by a different atom or group of atoms
What is an addition reaction?
A reaction where an atom or group of atoms is added to a molecule without taking anything away
What is combustion?
Combustion is burning a substance, and is a reaction with oxygen
What is crude oil?
A mixture of hydrocarbons
Explain how crude oil is separated into fractions
Crude oil is separated by fractional distillation. Crude oil is heated and the oil evaporates. It then goes into the tower. As the vapours rise up the tower the temperature falls. Different sized fractions condense at different heights because they have different boiling points. Smaller molecules condense high up the tower. Larger molecules condense low down in the tower. Then the fractions are collected.
What is the name of the process in which crude oil is separated into its various components?
Recall a use of bitumen
Recall a use of diesel
Fuel for lorries
Recall a use of fuel oil
Fuel for ships
Recall a use of gasoline
Fuel for cars
Recall a use of kerosene
Fuel for aeroplanes
Recall a use of refinery gases
Recall a use for each of the 6 fractions obtained from the fractional distillation of crude oil
refinery gases=cooking; gasoline=fuel for cars; kerosene=fuel for planes; diesel=fuel for lorries; fuel oil=fuel for ships; bitumen=surfacing roads
Recall the names of the main fractions obtained from crude oil, in order of lowest boiling point first
Refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen
Describe the trend in boiling points of the main fractions in crude oil
Boiling point increases as the number of carbon atoms (chain length) increase
Describe the trend in viscosity of the main fractions in crude oil
Viscosity increases as the number of carbon atoms (chain length) increase
In the fractional distillation of crude oil, how does boiling point change as the chains get longer?
In the fractional distillation of crude oil, how does viscosity change as the chains get longer?
What is meant by the term viscosity?
The viscosity of a fluid describes how easily it flows. Water has a low viscosity, it flows very easily. Crude oil has a higher viscosity than water, it does not flow very easily.
Which fraction of crude oil has the lowest boiling point?
Which fraction of crude oil is the most viscous?
What does volatile mean? Which fraction of crude oil is the most volatile?
If a substance is volatile it evaporates easily. Refinery gas is the most volatile fraction of crude oil.
What is a fuel?
A fuel is a substance that, when burned, releases heat energy
What is a substance called if it, when burned, releases heat energy?
Recall the products of the complete combustion of alkanes
Carbon dioxide and water
Recall the products of the incomplete combustion of alkanes
Carbon, carbon monoxide, carbon dioxide and water
What is produced when alkanes burn with insufficient oxygen?
Carbon monoxide and water (and possibly also carbon and carbon dioxide)
Write a chemical equation for the complete combustion of propane
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
Explain why carbon monoxide is dangerous to humans
It is poisonous because it reduces the capacity of the blood to carry oxygen
Why does incomplete combustion occur?
When there is an insufficient supply of oxygen for complete combustion
State the catalyst for the cracking of hydrocarbons
State the conditions for the cracking of hydrocarbons
Aluminium oxide catalyst heated to 600°C
State the temperature for the cracking of hydrocarbons
What is cracking?
The breaking down of long-chain alkanes into alkenes and shorter-chain alkanes
When long chain alkanes are cracked, what is produced?
Shorter chain alkanes and alkenes
Write a chemical equation for the cracking of decane
C₁₀H₂₂ → C₂H₄ + C₈H₁₈
Crude oil contains a surplus of long chain alkanes and there is much higher demand for shorter chain alkanes. What process is used to deal with this imbalance?
Explain why cracking is an important process in the oil industry
Cracking converts long chain hydrocarbons into short chain hydrocarbons. Crude oil contains a surplus long chains. Shorter chain hydrocarbons are in greater demand, e.g. petrol. Cracking also produces alkenes which are used in making polymers and ethanol.
State the general formula of alkanes
State the names and molecular formulae of the first 5 alkanes