Question

Identify A,B and C as an alkane, alkene or an aromatic hydrocarbon.

Answer 1

@ganeshie8 @nincompoop @robtobey

Answer 2

@aaronq

Answer 3

can you post it as a pdf? word documents are sketchy

Answer 4

A is definitely an alkene.As only they react with Bromine water :p

Answer 5

A IS AN ALKENE, B IS ALKANE AND C IS AROMATIC HYDROCARBON


Alkenes and bromine water

Using bromine water as a test for alkenes

If you shake an alkene with bromine water (or bubble a gaseous alkene through bromine water), the solution becomes colourless. Alkenes decolourise bromine water.
The chemistry of the test
This is complicated by the fact that the major product isn't 1,2-dibromoethane. The water also gets involved in the reaction, and most of the product is 2-bromoethanol.
\[CH _{2}=CH _{2}+Br _{2}+H _{2}O \rightarrow Br -CH _{2}-CH _{2}-OH+HBr\]

However, there will still be some 1,2-dibromoethane formed, so at this sort of level you can probably get away with quoting the simpler equation:
\[CH _{2}=CH _{2}+Br _{2} \rightarrow Br -CH _{2}-CH _{2}-Br\]

Oxidation of alkenes with cold dilute potassium manganate(VII) solution

Experimental details

Alkenes react with potassium manganate(VII) solution in the cold. The colour change depends on whether the potassium manganate(VII) is used under acidic or alkaline conditions.

If the potassium manganate(VII) solution is acidified with dilute sulphuric acid, the purple solution becomes colourless.

If the potassium manganate(VII) solution is made slightly alkaline (often by adding sodium carbonate solution), the purple solution first becomes dark green and then produces a dark brown precipitate.

Chemistry of the reaction

We'll look at the reaction with ethene. Other alkenes react in just the same way.

Manganate(VII) ions are a strong oxidising agent, and in the first instance oxidise ethene to ethane-1,2-diol (old name: ethylene glycol).
FOR REACTION SEE http://www.chemguide.co.uk/organicprops/alkenes/kmno4.html