how i do this? (1 Viewer)

[muttiah]

Why does hexane decolorize bromine water in the presence of sunlight?
and what will b observed?

 

[toadstooltown]

Alkanes undego substitution reactions with Halogens but it's endothermic (hence requiring sunlight, I think) and is slow.

C6H12+Br2 -> C6H4Br + BrH
BrH isn't brown but strong acid which ionises sompletely, so no more colour.

 

[twilight1412]

Alkanes undego substitution reactions with Halogens but it's endothermic (hence requiring sunlight, I think) and is slow.

C6H12+Br2 -> C6H4Br + BrH
BrH isn't brown but strong acid which ionises sompletely, so no more colour.

well your equation is worng and i'll try explaing it a different way

he asked hexane not hexene ><

C6H14(aq) + Br (aq) ---> C6H8Br6 (aq) + Br (aq)

they react because its much easier for the H atoms to just break off and form a H2 to gain noble gas configuration and the Br in the water just replaces the H

this reaction takes place because the sun provides energy in the form of uv rays to start the reaction and is very slow

if left for extended periods of time then all the H will be replaced

C6H14(aq) + Br (aq) ---> C6Br14(aq) + Br (aq)

 

[Jono_2007]

Actually Bromine water is actually a base BrOH, due to the high reactivity of bromine, which undergoes a reaction with water forming BrOH.

 

[toadstooltown]

well your equation is worng and i'll try explaing it a different way

he asked hexane not hexene ><

C6H14(aq) + Br (aq) ---> C6H8Br6 (aq) + Br (aq)

Sorry, geeze, I'm used to everyone doing it with cyclohexane so I just wrote that without thinking. The principles still the same. Br2 is photodissociated much more easily than H2 and undergoes substitution until all Br2 is used up, which is why only a few drops are used, as a limiting reagent. This if for Bromine liquid

Bromine water, as Jonno_2007 said forms a base where the hydroxyl ion takes a hydrogen from the alkane and the bromine atom replaces it.

Twilight1412, please balance your equations, they make it seem that Bromine is in excess and not diatomic.