Alkenes (GCSE Chemistry)
Alkenes
Alkenes
- Alkenes are more reactive than alkanes. Alkenes are more reactive than alkanes because they are unsaturated. This means they contain a double bond between 2 of the carbon atoms in their chain.
- The double bonds in alkenes can open up. The double bond can open up and become a single bond. This means that the alkene can react with other molecules, making alkenes more reactive than alkanes.
- Bromine water reacts with alkenes. Bromine water undergoes a colour change when it reacts with an alkene. Therefore, it can be used to test for the presence of an alkene.
Reaction With Bromine Water
- Bromine water reacts with alkenes. As we’ve just seen, bromine water undergoes a colour change when it reacts with an alkene.
- Bromine is orange in colour. When bromine is on it’s own, it is orange in colour. When bromine is added to an alkene, a reaction occurs and the solution turns colourless.
- A ‘dibromo-‘ compound is formed when bromine reacts with an alkene. The solution formed in the reaction between bromine and an alkene is a ‘dibromo-‘ compound. For example, if ethene reacts with bromine, dibromoethane would be formed.
Uses of Alkenes
- Alkenes are used as starting materials. A major use of alkenes is as a starting material for other compounds. An example of this is in the formation of polymers, discussed earlier.
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