1.5 Other Useful Substances from Crude Oil Flashcards
What is cracking?
The splitting up of larger molecules into smaller, more useful molecules
How are molecules cracked?
Heating the molecule to vaporise it. Passing the vapour over a catalyst.
What is the formula for an alkene?
CnH2n
What is the test for alkenes?
Reacting with bromine water, turning it from orange to colourless
How are hydrocarbons ‘cracked’?
The hydrocarbons are heated to vaporise them. The vaporise hydrocarbon is passed over a powdered catalyst (aluminium oxide) at a high temperature (450ºC)
What type of reaction is cracking?
Thermal decomposition
What is the formula for alkenes?
CnH2n
Do alkenes have a double bond?
Yes
What’s the test for an alkene?
Adding the substance to bromine water. An alkene will turn the bromine water from orange to colourless
What’s the main products of cracking hydrocarbons?
Alkanes and alkenes
What’s an unsaturated hydrocarbon called?
An alkene
What’s polymerisation?
The joining together of small alkene molecules (monomers) to form very large molecules (polymers)
How is low density poly(ethene) made and what is its properties?
200ºC and 2000 atmospheres - flexible
How is high density poly(ethene) made and what are its properties?
60ºC and low pressure - rigid
Give some new uses of polymers (6)
- New packaging materials (biodegradable)
- Waterproof coatings for fabrics
- Dental polymers (tooth fillings)
- Wound dressings
- Hydrogels
- Smart materials (shape memory)
