In this I/GCSE Chemistry blog post, we will be looking into thr structure of alkenes, and to see the differences between alkane and alkene.
ALKENES
- The general formula for alkenes is CnH2n.
- The alkenes form another homologous series.
- In all the alkenes the hydrogen atoms are joined to other atoms by a single bond. The carbon atoms are also joined to one another by single bonds.
Carbon can also form double bonds, both with itself, and to oxygen and nitrogen.
Ethene is a flat symmetrical molecule. Carbon dioxide is a linear molecule.
ALKANES AND ALKENES COMPARED
Alkanes have their full quota of hydrogen atoms, and are said to be saturated. This makes them relatively unreactive.
Alkenes on the other hand do not have their full quota of hydrogen atoms and are said to be unsaturated.
- A carbon-carbon double bond is quite a strong bond, but it is also quite a reactive bond.
- It is quite readily partially broken into a carbon-carbon single bond with the addition of another atom taking place at each carbon atom.
- Bromine dissolved in water forms an orange brown solution, and when ethene is bubbled through it the orange colour disappears, as the bromine is used up in the reaction above. This constitutes the standard test to distinguish between an alkene and an alkane.
- An alkene decolourises bromine water rapidly, whereas an alkane does not.
- Ethane (unsaturated with a double carbon bond) + bromine = 1,2- dibromoethane (saturated with a single carbon bond).
- A major similarity between alkanes and alkenes is that both groups burn to produce carbon dioxide and water.
That is all to know about alkenes!
References:
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.freeexamacademy.com%2Falkenes%2F&psig=AOvVaw01n1QicH1zqX8aegVIWPz7&ust=1627837303053000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCLisjtbkjfICFQAAAAAdAAAAABAD
https://www.google.com/url?sa=i&url=https%3A%2F%2Fqsstudy.com%2Fchemistry%2Fdescribe-solubility-alkanes-alkenes-alkynes&psig=AOvVaw1k8-LBe8mRipnJfpTyf7aD&ust=1627837332712000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCIiUoeLkjfICFQAAAAAdAAAAABAJ
Drafted by Venetia (Chemistry)