What two elements make up a hydrocarbon?
Hydrogen and Carbon
What is crude oil a mixture of?
The ancient remains of plankton and other marine organisms is the origin of what finite resource?
What is the general formula for a homologous series of alkanes?
Draw the structure of and write the formula for the following alkanes:
a) Methane, CH4
b) Ethane, C2H6
c) Propane, C3H8
d) Butane, C4H10
What process is used to separate the hydrocarbons found in crude oil?
Name three useful fuels obtained from crude oil.
Any three from:
- heavy fuel oil
- liquefied petroleum gas
Name two useful materials that can be made from crude oil by the petrochemical industry.
Any two from:
Explain how fractional distillation of crude oil works.
• Crude oil (a mixture of different length hydrocarbons) is heated.
• Different length fractions have different boiling points. When heated, the fractions evaporate and rise up the tower.
• The fractions cool down as they rise up the tower. When they reach their condensing point, they will condense, turn into a liquid and flow out of the tower.
What is the relationship between the length of a hydrocarbon and…
a) The longer the hydrocarbon, the higher the boiling point (or vice versa)
b) The longer the hydrocarbon, the higher the viscosity (or vice versa)
c) The longer the hydrocarbon, the lower the flammability (or vice versa)
What type of reaction is shown by the equation below?
CH4 + 2O2 → CO2 + 2H2O
What are the products of complete combustion of a hydrocarbon?
carbon dioxide (CO2) and water (H2O)
Write a balanced equation for the complete combustion of …
C3H8 + 5O2 → 3CO2 + 4H2O
2C2H6 + 7O2 → 4CO2 + 6H2O
Describe the conditions needed for:
a) Catalytic cracking
b) Steam cracking
a) Catalyst (Aluminium oxide) and high temperature
b) Steam and high temperature
What are the products of cracking?
Alkanes and Alkenes
What is the test for an alkene?
• Add bromine water
• Turns from orange to colourless
Which are more reactive? Alkanes or Alkenes?
a) Complete the equation below:
C8H18 → C4H10 + _______
b) What process is shown by the equation above?
* This is just an example, you will have to complete any equation for this process.
a) C8H18 → C4H10 + C4H8
Why is cracking useful for modern life?
• Alkenes (that are made from cracking) are used to make polymers
• Alkenes (that are made from cracking) are used as the starting material for the production of many chemicals
• Cracking produces short hydrocarbons that makes useful fuels
Separate Q. What is the general formula for an alkene?
Separate Q. Draw the structure of and write the formula for the following alkenes:
a) Ethene, C2H4
b) Propene, C3H6
c) Butene, C4H8
d) Pentene, C5H10
Separate Q. Why are alkenes classes as ‘unsaturated’?
They contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms. (e.g. propene contains two fewer hydrogen atoms than propane)
Separate Q. What is the functional group of an alkene?
Separate Q. Why do alkenes tend to produce a smoky flame when they are burned in air?
Due to incomplete combustion (when there is insufficient oxygen).
Separate Q. What happens to the double carbon-carbon bond of an alkene when alkenes react with hydrogen, oxygen or a halogen?
The double carbon-carbon bond becomes a single carbon-carbon bond because atoms are added.
Separate Q. Describe the conditions needed for the following reactions:
a) alkene + water
b) alkene + hydrogen
a) High Temperature and a catalyst
b) Nickel Catalyst and 60 oC
Separate Q. Complete the equation below by drawing the structural formulae of the products of the reaction:
*this is just an example, you need to be able to do this for any reaction between the first four alkenes (ethene, propene, butene, pentene) and water, hydrogen, chlorine, bromine or iodine.
Separate Q. Describe the reactions between:
a) an alkene and hydrogen
b) an alkene and water
c) an alkene and a halogen
a) An alkene reacting with hydrogen is a hydrogenation reaction. The double carbon-carbon bond opens up and Hydrogen atoms are added. An alkene turns into an alkane.
b) When alkenes react with steam an alcohol is formed.
c) When an alkene reacts with a halogen, the double carbon-carbon bond opens up and halogen atoms are added. The molecule becomes saturated.
Separate Q. What is the functional group for an alcohol?
Separate Q. Draw the structure of and write the formula for the following alcohols: