Chemistry build up and aftermath

Idjit · 17-06-2009 9:15am

if anyone did ordinary here...did you guys know what the 'flavouring agent' was that was mentioned in one of the questions. It was the q with 4 compounds that u had to name and it sed one of them was used as a popular flavouring agent. anyone get it?

Crystler · 17-06-2009 10:08am

Jade182 wrote: »

if anyone did ordinary here...did you guys know what the 'flavouring agent' was that was mentioned in one of the questions. It was the q with 4 compounds that u had to name and it sed one of them was used as a popular flavouring agent. anyone get it?

Was the flavouring agent not vinegar? and it was ethanoic acid (that came up in the honours paper too :S

Crystler · 17-06-2009 10:09am

Aisling(",) wrote: »

its done
i dont care anymore
yay

AGREED! Thread should close now. A day after the exam finishes, all that can be discussed has been.

andyman · 17-06-2009 11:56am

Or maybe people like to give their opinions. It is a forum after all.

Anyway, what an unbelievable paper! So easy and I was panicking so much beforehand.

Q1 - Was gutted to see this one at first, but then I got started on it and it was actually very nice! I didn't get the b part fully right (the standerdisation of KMn04) but I'm pretty sure I got the rest of them right.

Q2 - Easiest experiment question I've ever seen! It was absolutely ridiculous. Was delighted when I saw the questions. The easiest 10-12% you can get!

Q3 - When flicking through it I just saw loads of clock glasses and I was like, what?? But again, once I started doing the questions it was grand.

Q4 - Was the first symbol "Oxidising" or something like that? Pretty sure I've seen it before. Other than that though it was easy, as per.

Q5 - Lovely, lovely question. Delighted to see First Ionistation Energy there.

Q6 - I looked at it and I didn't know what hydrocarbons or structural isomers were and reckoned it would be a disaster bar the last part. Then I got to actually doing it and once again, it was fine. It all came back into my head and it was a grand aul question.

Q8 - Too easy. Way too easy.

Q10 - Did A and C. Kinetic Theory of gases I didn't know at all. Other than that, absolutely fine. The C part... LOL!

Q11 - Oh come on! At least challenge us. A and B here. I can't believe they awarded us 3% for writing an expression for Kc and stating the effect of a catalyst on the value of Kc. That's an absolutely obscene amount of marks for something so simple. Then you had the B part, lovely!

After that disastrous Accounting exam yesterday, this is exactly what I needed to end the exams. Like I've said, at first look I was ready to cry. But then I actually got down to it was plain sailing. A1 please God.

Piste · 17-06-2009 12:43pm

JSK 252 wrote: »

You could also say the addition of oxygenates. Basically all the ways the octane number of a fuel is increased.

The question asked for ways in which the structure is changed though, not necessarily to raise to octane no (which is why I wrote polymerisation). Do oxegenates actually change the structure of hydrocarbons? I wasn't sure so I didn't write it, but it was something I was wondering.

candlegrease · 17-06-2009 1:32pm

So what was the ester? i said methyl propanoate.

Also, is ethanal the substance that ethanol is changed to as a primary metabolite?

smndly · 17-06-2009 1:35pm

candlegrease wrote: »

So what was the ester? i said methyl propanoate.

Also, is ethanal the substance that ethanol is changed to as a primary metabolite?

Ethyl ethanoate i thinks!

andyman · 17-06-2009 1:40pm

smndly wrote: »

Ethyl ethanoate i thinks!

This.

......H......O
,,,,,,|,,...//
H - C - C
,,,,,,|,,,,,\
,,,,,,H,,,,,,O - C2H5

2 carbons and then an ethyl group = Ethyl Ethanoate.

17-06-2009 1:44pm

Didn't everything on that list begin with eth? I put down ethanol, ethanal, ethanoic acid and ethyl ethanoate, anyway.

andyman · 17-06-2009 1:55pm

Yeah they did. I did out all the structures on the paper before I tackled the question to make sure.

A - Ethanol
B - Ethanal
C - Ethanoic Acid
D - Ethyl Ethanoate

JSK 252 · 17-06-2009 2:01pm

Piste wrote: »

The question asked for ways in which the structure is changed though, not necessarily to raise to octane no (which is why I wrote polymerisation). Do oxegenates actually change the structure of hydrocarbons? I wasn't sure so I didn't write it, but it was something I was wondering.

I wouldnt go as far and say that the chemical structure changes. Oxygenates change the physical properties of fuels to make them burn more easily so it does manipulate the structure.

HQvhs · 17-06-2009 2:08pm

I don't think oxygenates change the structure. They only increase the overall octane number of a fuel, such as petrol. Since petrol is a mixture of compounds it mightn't change the structure.

Des23 · 17-06-2009 2:15pm

Ya I was tempted to put down oxygenates but I said dehydrocyclisation and isomerisation in the end. I wasn't really sure how oxygenates actually raised the octane number.. is it just by being a good fuel that they help or do they do something chemically?

It was the 'structural changes' that they asked for..

aine-maire · 17-06-2009 2:17pm

I said dehydrocyclisation and addition.

Not so sure about addition, but it's kind of changing the structure if they add halogens to the molecule,isn't it? It's making it into something different anyway, right?

Piste · 17-06-2009 2:20pm

I think addition is like polymerisation

aine-maire · 17-06-2009 2:24pm

Piste wrote: »

I think addition is like polymerisation

Well not really, because addition is adding something new to the molecule, whereas polymerisation is just joining lots of the same molecules together afaik....

But I guess if addition were right, polymerisation would be too,in that kinda way.!

Des23 · 17-06-2009 2:25pm

aine-maire wrote: »

I said dehydrocyclisation and addition.

Not so sure about addition, but it's kind of changing the structure if they add halogens to the molecule,isn't it? It's making it into something different anyway, right?

I don't think adding halogens would increase the octane number though..

And wouldn't polymerisation lower the octane number by making the unbranched alkane chain longer..

Idjit · 17-06-2009 2:26pm

Does anyone know a site with the solutions up for the chem exam?I'd love to check a few things that i know i got wrong that have been driving me mad.

aine-maire · 17-06-2009 2:27pm

Des23 wrote: »

I don't think adding halogens would increase the octane number though..

It didn't say anything about octane numbers.
It asked for ways in which they 'change the structure'...
And adding halogens would kinda change the structure...and they do do that in the petrochemical industry because they're such good solvents!

I think

Piste · 17-06-2009 2:29pm

Des23 wrote: »

I don't think adding halogens would increase the octane number though..

And wouldn't polymerisation lower the octane number by making the unbranched alkane chain longer..

It would, but that's not what the question asked. The question was "name two other processes carried out in oil refineries to modify hydrocarbon structures"

Des23 · 17-06-2009 2:33pm

Piste wrote: »

It would, but that's not what the question asked. The question was "name two other processes carried out in oil refineries to modify hydrocarbon structures"

Yup, your right, I was remembering it wrong in my head. My bad.

galway.gaa · 17-06-2009 4:19pm

Piste wrote: »

It would, but that's not what the question asked. The question was "name two other processes carried out in oil refineries to modify hydrocarbon structures"

the question said other as you can see and the other one was cat cracking so i think the correct answer is isomerisation and reforming:cool:

OxfordComma · 17-06-2009 4:52pm

galway.gaa wrote: »

the question said other as you can see and the other one was cat cracking so i think the correct answer is isomerisation and reforming:cool:

Yeah, that's what I said too...

It's starting to worry me a bit because everyone's saying the paper was easy... I hope they don't end up marking it really hard! Like they shouldn't give us an easy paper and then punish us as a result! (... and to be perfectly honest, I didn't think it was any easier than any other paper I'd done...)

aine-maire · 17-06-2009 5:11pm

Did anyone know what the aldehyde found in almond kernels was?

Des23 · 17-06-2009 5:13pm

benzaldehyde.

CallMeDoctor · 17-06-2009 5:13pm

aine-maire wrote: »

Did anyone know what the aldehyde found in almond kernels was?

Ya benzaldehyde answer was in the q reli i wudnt have none it otherwise!:cool:

aine-maire · 17-06-2009 5:20pm

Oh no!
I thought it was some kinda benz- thing, but I couldn't remember what it was called, so I just said benzenal. (because the name benzoic acid follows the rules!)
I guess it's close...think I'll scrape any marks?

I knew it sounded wrong...:rolleyes:

Des23 · 17-06-2009 5:26pm

aine-maire wrote: »

Oh no!
I thought it was some kinda benz- thing, but I couldn't remember what it was called, so I just said benzenal. (because the name benzoic acid follows the rules!)
I guess it's close...think I'll scrape any marks?

I knew it sounded wrong...:rolleyes:

I don't know, I'd say you could nearly get away with it.

I mean all it is is a benzene ring with an aldehyde functional group attached so I think Banzanal should be acceptable..

CallMeDoctor · 17-06-2009 5:26pm

aine-maire wrote: »

Oh no!
I thought it was some kinda benz- thing, but I couldn't remember what it was called, so I just said benzenal. (because the name benzoic acid follows the rules!)
I guess it's close...think I'll scrape any marks?

I knew it sounded wrong...:rolleyes:

yup cause you practically had the aldehyde ending 'anal' but id say it was onli 3 marks ull prob get 2?

aine-maire · 17-06-2009 5:30pm

CallMeDoctor wrote: »

yup cause you practically had the aldehyde ending 'anal' but id say it was onli 3 marks ull prob get 2?

Meh,it's something...think I got all of the rest of that question right, so I'll settle for 2

Chemistry build up and aftermath

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