C 6.1 Other useful substances from crude oil Flashcards
(10 cards)
What is cracking?
A process that breaks down long-chain hydrocarbons into shorter, more useful hydrocarbons.
Why is cracking needed?
There is a high demand for short-chain alkanes (e.g. petrol) and alkenes for making plastics, but too many long-chain hydrocarbons from crude oil.
What are the conditions required for cracking?
High temperature and a catalyst (catalytic cracking), or high temperature and pressure (thermal cracking).
What are the products of cracking?
Short-chain alkanes and alkenes.
Give one use of alkenes.
Used to make polymers (plastics).
What is an alkene?
A hydrocarbon with at least one carbon-carbon double bond (C=C).
What is the general formula for alkenes?
CnH₂n.
How can you test for alkenes?
Add bromine water – it will turn colourless if an alkene is present.
Why do alkenes decolourise bromine water?
Because they are unsaturated and the double bond reacts with bromine.
What is the main difference between alkanes and alkenes?
Alkanes are saturated (only single bonds); alkenes are unsaturated (contain at least one double bond).
