Chemistry Salters F332 june 2010

Mate, it was four bromines.

LOOK.

If one C=C bond can facilitate 2 bromines, then two C=C can facilitate 4 bromines.

2 x 2 = 4. Simple

And remember, there were 2 lots of C=C.
Look at the bromination of alkenes again to see what I mean.

What were the 2 similarities and difference?

You can't expect the Br to replace the OH group.
Two reasons. Firstly, a reagent of HBr will be required. Secondly, you need to reflux to cause a nucleophilic substitution of OH to put in Br.

There was no heat at all. It was carried out at Room temp. (STP)

Sim: both have a colour change from orange to colourless

dif: the citronellol decolourises faster due to fewer bonds.

I deleted my message

But one C=C can only hold one more Bromine can't it? It already has 3 bonds. One more is freed up for one Bromine?

The similarities was a 3 mark question though and said similaritieS which suggests theres more than one?

The similarities was a 3 mark question though and said similaritieS which suggests theres more than one?

Sim: both have a colour change from orange to colourless

dif: the citronellol decolourises faster due to fewer bonds.

Sim: both have a colour change from orange to colourless

dif: the citronellol decolourises faster due to fewer bonds.

3 marks:

s: colour change (1) from orange to colourless (1)

d: faster reaction (1)

there was a 2002 paper that showed this in the mark scheme

thank god i have a photographic memory

Nope.

Once one Bromine attaches to the carbon, a carbocation is made.

mate, open up Chemical Ideas page 274.

see a diatomic molecule of bromine?

which means 2 Br's.

3 marks:

s: colour change (1) from orange to colourless (1)

d: faster reaction (1)

there was a 2002 paper that showed this in the mark scheme

thank god i have a photographic memory

I admit defeat

You're right. Yay for losing some more marks

yay thats wat i wrote.

Kiron, wat did u answer for the 2 reflux questions? I think one asked how you would carry it out in the lab and the other was why u need to use a reflux for this reaction.

The Similarities was worth (3) marks on its own.
Differences was worth (2).

So for the colour change can understand brown to colourless as (2) marks?

I guess you might get 2 marks for saying which one was a faster reaction to get you (2) on the second?

For the ppm, I got 1.4, as the thing was in a ratio. (1-1000)

Then for the percentage, I got around 0.044 of nitrogen (3.5/78)

For the question about why we would reflux I put

to ensure nothing is lost (evaporation) by using the cooling jacket
and to ensure it is completely reacted/oxidised.

any thoughts?