Sweet sweet chemistry

acri

Anyone have any tips on this, the most wonderous of all subjects? Or at least know where I can find any? Anything to aim for would be most helpful.

Scarinae

Everyone's saying bleach experiment, winkler experiment, I can't remember what else but do a search and you should find the predictions threads

sixdraw

preperation of ethanoic acid.i think its one of the only organic preperations that hasn't been up yet, not sure though. have a look at the comparison of the halogens as oxidising agents and le chatelier's exp.s and flame tests.
clove oil aswell has only been up in sec. B , quite a lot they can ask on it so they might put it in.

(I accept no responsibility for a failed exam though)

Cherry_Pie

pH is tipped for a ques this year!!! Appartently something about the pH of water is due up!

Matthewthebig

Winkler will be on it!
trust me

Cherry_Pie

Yup! I was told Winkler at the Easter grinds in the institute!

acri

Ah, many thanks. Damn this course. heh heh, winkler...

StevieK5000

Don't go in without knowing this:

1. Primary alcohol oxidises to Aldehyde oxidises to acid

2. Secondary alcohol oxidises to Ketone

I'll eat my shoe if some reference to this doesn't come up. High probability of being a big question!!!!

2e

StevieK5000 wrote:

Don't go in without knowing this:

1. Primary alcohol oxidises to Aldehyde oxidises to acid

2. Secondary alcohol oxidises to Ketone

I'll eat my shoe if some reference to this doesn't come up. High probability of being a big question!!!!

What size shoe are you????

acri

StevieK5000 wrote:

Don't go in without knowing this:

1. Primary alcohol oxidises to Aldehyde oxidises to acid

2. Secondary alcohol oxidises to Ketone

I'll eat my shoe if some reference to this doesn't come up. High probability of being a big question!!!!

I'm not taking any chances on the organic chemistry. I'm just gonna do it all. 40% of the test is on organic alone and it's not difficult. Just loadsa little finniky bits. I hope, for your sake, those quoted references come up.

Cherry_Pie

In Chemistry Live theres a graph on page 382! I would suggest everone knows it and knows how to use it!!!! Its a great help if you can to it!! To learn it, cover the bottom half of the page , alcohols down and learn those links, very easy, it, Petroleum - Alkane - Haloalkane ect. Then learn the bottom half of the page, more complicated but easy to learn in a small chunk! Then put the two together!! It'll save your ass for organic!!!

Cherry_Pie

It's all about chemistry
It's all about chemistry
Oh-oh-oh-oh-oh, oh

It's all about chemistry
It's all about chemistry
Oh-oh-oh-oh-oh, oh

Richard_Fonzie

I dont see why the Winkler method should come up. Perhaps it hasn't been up before, but there was an enviromental chemistry/water experiment up last year (hardness). This year I think it's going to be Bleach (or iodine + thiosulfate), preparation of Ethanal/Ethanoic/Clove Oil and an Equilibrium one (probably le chateliers).

My reasoning: At least one of each of a Organic Chemistry and a Titration usually come up every year, each of these hasn't come up before, chemical equilibrium has come up in 2 out of 3 papers (and didn't come up last year) and enviromental chemistry/water has come up in 1 out of 3 papers (and did come up last year). I'm probably going to be only doing 2, but I'm fairly certain that at least 2 of the ones from titrations/organic chemistry/chemical equilibrium that haven't come up before will come up this year.

the smiley one

Richard_Fonzie wrote:

but I'm fairly certain that at least 2 of the ones from titrations/organic chemistry/chemical equilibrium that haven't come up before will come up this year.

A titration and an organic experiment HAS to come up (Q1 and 2). The third question is the rest of the mandatory exps...(cloves and bezoic are included in organic btw).

Well at least that's what I've been told for the last 2 years...



Edit: In my haste I think I read your post wrong...just so everyone knows...

Richard_Fonzie

They dont HAVE to come up, it's just that they're extremely likely to come up. Take last year for example, an organic chemistry one did come up, but the Titration one was from the Enviromental Chemistry/Water section. 17 of these experiments in all btw, but 6 have come up and some are very simple/straight forward (like preparation of standard solution of sodium carbonate).

the smiley one

Richard_Fonzie wrote:

They dont HAVE to come up, it's just that they're extremely likely to come up. Take last year for example, an organic chemistry one did come up, but the Titration one was from the Enviromental Chemistry/Water section. 17 of these experiments in all btw, but 6 have come up and some are very simple/straight forward (like preparation of standard solution of sodium carbonate).

I think we are getting our wires crossed here and we are sayiny the same thing
A titration and
An organic exp
comes up every year , without fail.

That's all I was saying....doesn't matter....

sci0x

My Chemistry teacher said that if he was setting the paper, he would set something that was given in the last 3 years in spite of all of us trying to guess of what they could ask that has nver come up.

Anyway, they have a habit of asking questions that they give out as additional questions in the exam papers. They sometimes take the exact question from the additional questions and throw it onto the paper. So take a look at all of those Qs especiall the exps ones which are "the preperation of ethanal" with Qs asked on the prep of ethanoic acid in it so would be a good question.

acri

Generally I think papers are quite predictable, but still, any tips are still useful. Soap, Ethanol, Ethanoic Acid and Equilibrium reactions are the only exps I'm revising.

Richard_Fonzie

the smiley one wrote:

I think we are getting our wires crossed here and we are sayiny the same thing
A titration and
An organic exp
comes up every year , without fail.

That's all I was saying....doesn't matter....

Yes we are , but I was just saying that they *could* pull a fast one (and they kind of did it last year) and screw alot of unsuspecting people out of an experiment!

Breezer

They could but volumetric analysis and organic chemistry are two of the most important sections of the course as it relates to chemistry in the real world (apparently) so it's doubtful. But they've already thrown up a few surprises in other subjects so you never know

JackKelly

i also heard that a water of cyrstallisation could be up this year.

sci0x

These are the exps im looking over:
Concentration of sodium hypochlorite present in bleach
Rate of decomposition of hydrogen peroxide using manganese dioxide as a catalyst
Clove Oil
Preperation of ethanoic acid
Washing soda
Heat of Neutralisation
Preperation of Ethanal
Flame tests and anion tests could all be asked in one question
Winkler
Equilibrium Exps

Cotsy

Anyone know whats the test to distinguish between ethanal and ethanoic acid? In my mock i said the differnet boiling points but got 0 marks so i guess that wasnt what they were lookin for.

phantom_lord

Test for acidity i guess...one's an acid...

Cotsy

ye was thinking that, thanks nyway.

CoffeeFreak

Cotsy wrote:

Anyone know whats the test to distinguish between ethanal and ethanoic acid? In my mock i said the differnet boiling points but got 0 marks so i guess that wasnt what they were lookin for.

One test would be adding acidified KMNO4, for ethanal, it will decolourise, but it won't for ethanoic acid because it can't be oxidised any more. The KMNO4 gets reduced from 7+(purple) to 2+(colourless) as the ethanal is oxidised.

phantom_lord

The chem course isn't that big, would you not just do all 28exp. They're pretty much the same anyway(the titrations i mean) and there's not much in the rest.

Cotsy

cool good stuff, as you can see i'm pretty screwed for this test.

JackKelly

Also, fehlings solution (goes from Cu2+ to Cu+1 , Red to Blue...i think?), or tollens reagent (amonical silver nitrate, a silver deposit is left on the inside of the test tube) both prove its a aldehyde.....i've been studing!

Cherry_Pie

I was told a water experiemnt has come up every year and the Winkler is the only Water experiment NOT to have been on the paper yet! So Im just saying, Im going in there knowing it!! This its better to at least read over it than not!

acri

I think the "If it hasn't come up yet it's definatley coming up this year" method of prediction only works if it's the last year of the course (i.e. English). I've a funny feeling Benzoic Acid recrystallisation is a-comin up and almost certain a Le Chatelier's Principle. As regards section B, havn't a clue. But again, I think if I know the Option, Water and Organic, there's about 70/80% of your test right there.

Richard_Fonzie

^^^
If you're talking about Section A, that's not correct. From the 4 papers (2001 sample, 2002, 2003, 2004) only one of them has featured a 'water' experiment, and that was last year. Water questions do come up in Section B (but by that logic so does every single other major topic) and there seems to be a 7-mark short question in Q.4 every year, but they're not worth very many marks (7 in 2004; 18 + 7 in 2003; 7 + 50 in 2002) compared to other topics you could be focusing on. My guess is that there'll be half a question (18-25 marks) in section B this year.

Richard_Fonzie

acri wrote:

I think the "If it hasn't come up yet it's definatley coming up this year" method of prediction only works if it's the last year of the course (i.e. English). I've a funny feeling Benzoic Acid recrystallisation is a-comin up and almost certain a Le Chatelier's Principle. As regards section B, havn't a clue. But again, I think if I know the Option, Water and Organic, there's about 70/80% of your test right there.

Benzoic Acid came up last year

sci0x

No reason why they wouldnt ask it again if i was badly answered last year or ask it in one of the questions rather than as an exp this year

acri

Richard_Fonzie wrote:

Benzoic Acid came up last year

That's not gonna stop it come up this year.

Cherry_Pie

I wasn't talking about Section A! I was talking about anywhere in the paper! If you go over all the papers so far there has been a water experiment in there somewhere!! Its not my prediction though, I was told that in the institute last Easter. Anyway, Im speed reading the entire book and going over anything I find I don't know! Because really the only way you can be ready for this paper is to know everything! Youre dead right when you say its not English or something, Chem is quite difficult to predict!!!!

Good Luck to everyone!! Hope you all do well!!

Cherry_Pie

http://www.education.ie/servlet/blobservlet/lc_chemistry_sy.pdf

And heres a link to the Chem Syllabus!!

Richard_Fonzie

That's not gonna stop it come up this year.

In Section A it is. Otherwise you might as well just learn every single experiment.

The syllabus doesn't really help, because it just tells you what's on the course, rather than how the examiner sets a paper (I have the edco papers to go on for that...).

Good Luck to everyone!! Hope you all do well!!

Thanks

Cherry_Pie

Your Welcome!

Syllabus can help if your really lost!! Use it was a check off list for final revision cram sessions!! Break up the time you have by the time it says for the teachers to spend on each part!!! If your on track then nope you wont need it!!!

deek

Erm ok sorry about this Ive tried looking in the syllabus for this but just got utterly confused! Do we have to know all the chromatography experiments i.e tlc,paper etc.
I know we have to know gas and HPLC, u.v and infra-red im just talking about the experiment ones. Any help would be soo good cos I really dont have a clue! :rolleyes:

scorpy

yeah, I think you have to know all the experiment ones. they're not too hard anyway.

Cotsy

I'm no expert but i think u only have to know 1 type of Thin Layer, Paper and column

sci0x

I've seen questions though specific to thin layer chromotography, and questions like what this process is better than paper chromatography.

deek

Hmmmm and the mystery continues...................

sixdraw

chemistry has to be the hardest subject to learn. I had everything done really well until the start of the exams and I have to start all over again tonight. It just doesn't seem to stick

Doctor D-Man

do do doo doo dooo dooooo de de de de. hmm... x-files tune doesnt really work like that does it. Chromatogogographigrams eh... in my day - when i actually worked at chem last year we just did paper chromowatchamacallit but thats just my class. anyway, there never really a big question on it afaik.

All we did was put ink on a piece of paper and watch it run...what more can I say

Richard_Fonzie

^^^
That's what it feels like for me. I had the same feeling going into Physics (after staying up until 3 to study..), but everything worked out fine. When you're under pressure, it comes back to you, and a little study the night before reinforces it (at least for me).

Cherry_Pie

:mad: Im the same!!! Got amazing results all year and today its all just GONE!!!!

HELP!!!!!!!!

the smiley one

deek wrote:

Erm ok sorry about this Ive tried looking in the syllabus for this but just got utterly confused! Do we have to know all the chromatography experiments i.e tlc,paper etc.
I know we have to know gas and HPLC, u.v and infra-red im just talking about the experiment ones. Any help would be soo good cos I really dont have a clue! :rolleyes:

afaik, you have to know one of the chromatography exps (most people do the paper one). However you have to know the theory and processes to the 2 other ones ie. HPLC and Gas. You also have to know the UV IR absorption spectra....but they are kinda different....oh, and you have to know uses for all of them.

Our teacher gave us notes from the syllabus on instrumentation so it should be all there. Hoped that helped!

StevieK5000

2e wrote:

What size shoe are you????

5000

the smiley one

Cherry_Pie wrote:

:mad: Im the same!!! Got amazing results all year and today its all just GONE!!!!

HELP!!!!!!!!

Calm!!! It's in there somewhere, and even if you get into the exam and you think you don't know the answer to the stuff, think it out logically...a lot of the stuuf is common sense if you think about it. You obviously know a good bit of chemistry, so I wouldn't wortry too much - just do lots of exam papers and look up the answers at www.examinations.ie to hone your exam technique.

You'll be fine!!