Alkene/Alkane Prac (1 Viewer)

[Danger]

We have a prac assessment on identifying alkanes/alkenes with bromine water coming up. Just wondering, will they test you on cyclohexane/cyclohexene again since we have already done that in class? Also, what are the appropriate equations?

 

[brenton1987]

Also, what are the appropriate equations?

Acyclic Alkanes:
C_nH_2n+2 + Br₂ --> No Reaction

Acyclic Alkenes:
C_nH_2n + Br₂ --> C_nH_2nBr₂

Cyclic Alkanes:
C_nH_2n + Br₂ --> No Reaction

Cyclic Alkenes:
C_nH_2n-2+ Br₂ --> C_nH_2n-2Br₂

 

[davidbarnes]

Whats the differernce between cyclic and acyclic?

 

[Forbidden.]

Whats the differernce between cyclic and acyclic?

Cyclic alkanes have a ring structure (Hexagonal in the case of cyclohexane) whereas acyclic alkanes have a linear (straight) structure (Like hexane).

EDIT:

Visually compare -

Hexane

Cyclohexane

EDIT2: Link to picture of hexane structure fixed.

 

[IMTB]

We have a prac assessment on identifying alkanes/alkenes with bromine water coming up. Just wondering, will they test you on cyclohexane/cyclohexene again since we have already done that in class? Also, what are the appropriate equations?

u will need to know the exp for hsc

 

[beentherdunthat]

^^ Yer. It's realli easy. It's basicali theory.

 

[dr baby beanie]

I got told by my chem teacher that if you were asked to give an equation you could say that ethene and ethane represents the cyclohexanes and cyclohexenes, ie their equivalent bonding structures - if you get me.

 

[undalay]

Since it's bromine water wouldn't they expect HOBr instead of Br₂

Br₂ + H₂O <---> HOBr + Br^- + H⁺


Acyclic Alkenes:
C_nH_2n + HOBR --> C_nH_2nBrOH


Cyclic Alkenes:
C_nH_2n-2+ HOBR --> C_nH_2n-2BrOH

 

[kaliber]

the cyclohexene under go addition reaction, which is instantaneous (turns colourless)
the cyclohexane, although you dont see any change it actually does under go Substitution reaction but this process takes several hours - days under the presence of UV light

 

[gcmk]

yes it should be HOBr since it is bromine WATER not liquid.

 

[xiao1985]

^correct. though there's a much more profound reason why Br and OH are added.

the end results are the same though.