Chemistry Salters F332 june 2010 Watch

kironkabir
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#501
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#501
(Original post by hollywoodbudgie)
See that's what I did as well, but i also put a Br where the OH group
was... I'm really not sure if that was a smart move on retrospect. :sad:
Tell me what you guys think.

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)
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Doctogan
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#502
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(Original post by kironkabir)
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.
I deleted my message :p:

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?
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kironkabir
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#503
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#503
(Original post by hazzawazza19)
What were the 2 similarities and difference?
Sim: both have a colour change from orange to colourless

dif: the citronellol decolourises faster due to fewer bonds.
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hollywoodbudgie
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#504
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#504
(Original post by kironkabir)
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)

:facepalm: I'm such an idiot! >_<
I should never check my work again to do 'corrections'
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hazzawazza19
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#505
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#505
(Original post by kironkabir)
Sim: both have a colour change from orange to colourless

dif: the citronellol decolourises faster due to fewer bonds.
The similarities was a 3 mark question though and said similaritieS which suggests theres more than one?
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kironkabir
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#506
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#506
(Original post by Doctogan)
I deleted my message :p:

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?

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.
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kironkabir
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#507
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(Original post by hazzawazza19)
The similarities was a 3 mark question though and said similaritieS which suggests theres more than one?

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
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hollywoodbudgie
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#508
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#508
(Original post by hazzawazza19)
The similarities was a 3 mark question though and said similaritieS which suggests theres more than one?
You had to explain them as well
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mattmitch22
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#509
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#509
(Original post by kironkabir)
Sim: both have a colour change from orange to colourless

dif: the citronellol decolourises faster due to fewer bonds.
I put the similarity was that, after each shake, both would turn clear

As the difference, i put that the one with one double bond would stop this colour change earlier than the 2 double bonded one would (twice as much bromine is required for double bonded one)
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mhasan
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(Original post by kironkabir)
Sim: both have a colour change from orange to colourless

dif: the citronellol decolourises faster due to fewer bonds.

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.
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hollywoodbudgie
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(Original post by kironkabir)
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
o_o Give me your memory.
Now.
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Doctogan
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#512
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#512
(Original post by kironkabir)
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.
I admit defeat :p:

You're right. Yay for losing some more marks :lol:
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hazzawazza19
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#513
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#513
(Original post by kironkabir)
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
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?
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hollywoodbudgie
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(Original post by Doctogan)
I admit defeat :p:

You're right. Yay for losing some more marks :lol:
:dance: join the club!

We have cookies!!!
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kironkabir
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#515
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#515
(Original post by mhasan)
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.

1: Oh, you need to use a condenser with anti-bumping granules. I waffled this one.

2: you need to reflux it because 1-bromobutane has such a low boiling point. if you didnt reflux it (cool it with water), all of it would evaporate instantly. that wouldnt be good for any chemist
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mhasan
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#516
(Original post by hazzawazza19)
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?

I'm quite sure similarities was not a 3 mark Q it was definately only 2 marks. I remember thinking straight away one mark for colour change and the other for specifying the colours.
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hazzawazza19
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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?
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Revolution is my Name
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#518
(Original post by cpdavis)
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)
What? For the first one, you had to multiply by 10,000 to get ppm, then divide by a thousand to get Deuterium, to get something 10 times more for the number given, surely?
And, for the second, wouldn't you need to multiply that amount by 91, given the greater pressure of the atmosphere of Venus?
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mariam-x
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#519
(Original post by hazzawazza19)
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?
I put that, too.
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JamesPen
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#520
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I put none of the products are lost

so no harmful and toxic gases are released.

Think ill get marks for that?
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