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So whatcha make of the Chemistry paper?

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2

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    #32
    G_Foster
    Closed Accounts Posts: 15 ✭G_Foster


    So yeah, there I was, dreading this exam! That + English 2 = Horrible day for me! But when I sat down, I was pleasantly surprised looking over the paper...

    Didnt have a clue bout the chromatography/steam distillation experiment, but the other two were fairly handy, especially the titration, that was my top prediction so had it learned pretty well! (P.S I think the acid in ant stings is commonly known as Formic Acid, our teacher told us that just before we went in, which was a weird coincidence ^^)

    And what was up with 11B? Seems like a new type of question to me, but i thought it was so so easy! Hopefully a nice 25 marks for me! (Unless i got it completely wrong, which would be just like me :o)


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    #33
    delta214
    Registered Users Posts: 227 ✭✭delta214


    Awww poops. I put propene too :( ahh well.
    Im hopin for a c1, I thought it was a real nice paper, if i had studied at all id say i wouldve gotten around a b1.


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    #34
    Calorimeterman
    Closed Accounts Posts: 64 ✭✭Calorimeterman


    I did pretty much all the calculations ( and took the liberty of writing them down on my exam paper). I don't think many other people would have done the same, but I got the theory pretty much perfect and the calculations are the only bit which may let me down.


    Q1
    moles per litre- 0.0906
    grams per litre- 5.436
    % w/v- 5.436%

    Q2
    why would anyone even dream of doing that question?? baffles me...

    Q3
    instantaneous rate- 5.128 cm3 per minute
    total mass 0.104g

    Q6
    Thermochemistry calculation- (-)1368 kj per mol

    Q6
    Equilibrium constant- 46.24

    Q8
    pH # 1- 0.3
    pH # 2- 2.5

    Q 11 b)
    Sooo... easy
    i 1144 g
    ii 26 mol
    iii 624 L
    SUV- 1152

    Please speak up if any of them ring a bell, they are pretty much what my A lies on!!!


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    #35
    Thomas_S_Hunterson
    Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    Michellenman wrote: »
    Ascorbic acid, whatever that is, it's possible i made it up though.

    It's Vitamin C actually:p


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    #36
    delta214
    Registered Users Posts: 227 ✭✭delta214


    1,6, and 11b are the same as what i got.
    Although for 11b) the last part was how much MORE litres of CO2


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    #37
    G_Foster
    Closed Accounts Posts: 15 ✭G_Foster


    I got pretty much the same calculation answers as you Calorimeterman,
    Q1, Q3, Q6 and Q11B were (from what I remember) exactly what I got! Unless we're both wrong :S Didnt do Q8, but for the equilibrium, I got an answer of 11-point-something :O Altho much more of a chance of you being right, I'm fairly bad at the aul equilibrium calculations myself! Hehehe..


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    #38
    Michellenman
    Registered Users Posts: 11,195 ✭✭✭✭Michellenman


    Sean_K wrote: »
    It's Vitamin C actually:p

    There's my junior cert home ec coming back to me!:p


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    #39
    pocket aces
    Registered Users Posts: 56 ✭✭pocket aces


    Calorimeterman wrote: »
    Please speak up if any of them ring a bell, they are pretty much what my A lies on!!!

    almost all of them ring a bell :D


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    #40
    Adventure
    Registered Users Posts: 81 ✭✭Adventure


    Methanoic acid for ant bites right?


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    #41
    G_Foster
    Closed Accounts Posts: 15 ✭G_Foster


    Yup, Methanoic acid (or Formic Acid) is the carboxylic acid found in ant stings :) Hope they accept formic acid, as i couldn't remember the systematic name for it :(


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    #42
    Parsley
    Closed Accounts Posts: 3,144 ✭✭✭Parsley


    Calorimeterman wrote: »
    Q1
    moles per litre- 0.0906
    grams per litre- 5.436
    % w/v- 5.436%-

    Yeeup.
    Calorimeterman wrote: »
    Q2
    why would anyone even dream of doing that question?? baffles me...

    Cos it was a piece of piss!
    Calorimeterman wrote: »
    Q3
    instantaneous rate- 5.128 cm3 per minute
    total mass 0.104g

    Yup, but I got around 5.6ish.
    Calorimeterman wrote: »
    Q6
    Thermochemistry calculation- (-)1368 kj per mol
    I forgot how to do it... :p
    Calorimeterman wrote: »
    Q6
    Equilibrium constant- 46.24
    Ohhh yeeeah!
    Calorimeterman wrote: »
    Q8
    pH # 1- 0.3
    pH # 2- 2.5

    Mmmhmm. :cool:


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    #43
    G_Foster
    Closed Accounts Posts: 15 ✭G_Foster


    Hey, I see a few people are getting an answer of 46.24 for Kc in Q7, could someone explain to me how? I got 11.56, which is a quarter of this... I'm fairly confused! I probably screwed up, just don't know where, any help is appreciated!


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    #44
    Turquoise
    Closed Accounts Posts: 94 ✭✭Turquoise


    Calorimeterman wrote: »
    Q1
    moles per litre- 0.0906
    grams per litre- 5.436
    % w/v- 5.436%

    Q3
    instantaneous rate- 5.128 cm3 per minute
    total mass 0.104g

    Q6
    Thermochemistry calculation- (-)1368 kj per mol

    Q6
    Equilibrium constant- 46.24

    Q8
    pH # 1- 0.3
    pH # 2- 2.5

    Q 11 b)
    Sooo... easy
    i 1144 g
    ii 26 mol
    iii 624 L
    SUV- 1152

    Please speak up if any of them ring a bell, they are pretty much what my A lies on!!!

    I wrote mine down too, always do...but our first one is different. In Q1 I got 0.11 moles originally. Is it not (25 x 0.1)/22.65 rather than (22.65 x 0.1)/25 ? I'm confused now - eek!

    My instantaneous rate was 4.4, but I'll admit it's not my strongest question, so yours is probably right.

    Thermochemistry and Equilibrium are exactly the same. ;) As are Q11. :)


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    #45
    starkinter
    Closed Accounts Posts: 59 ✭✭starkinter


    I also got 0.11 moles for the ethanoic acid, hence 6.6% w/v.

    I wasn't sure for the eqm. constant, I panicked in a small way. I think what I finally had was 46.24 crossed out and 11.56 written after it.

    People are always saying you get marks for crossed out correct answers, but I doubt that's actually true in this case, is it?


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    #46
    Undergod
    Registered Users Posts: 2,858 ✭✭✭Undergod


    Hmm, I got 46.24 as well, but I couldn't get the method in the book to work, I made up my own method on the spot, based on the Law of Conservation of Mass. It was mathematically and scientifically sound though, so hopefully it'll satisfy them.

    I have also been told (by teachers) you can get marks for crossed out answers but I'd say that only applies sometimes.


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    #47
    starkinter
    Closed Accounts Posts: 59 ✭✭starkinter


    Undergod wrote: »
    I have also been told (by teachers) you can get marks for crossed out answers but I'd say that only applies sometimes.

    Let's just hope that this is one of those cases so, because the rest of that question went grand.

    Do they ever not ask you to define Le Châtelier's Principle?


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    #48
    Heretic
    Registered Users Posts: 7 ✭Heretic


    I was really disappointed with the paper. I was hoping to get an A. I studied for so long and the paper was really hard I thought. I hope I get a B anyway... I got 0.11 M/L for the vinegar too. Was the coulor change for phenolphthalien colourless to pink as the base was in the conical flask? In the ethene Q I was stupid enough to think they asked for the structural isomer of an alkane... I knew the ones for Butene. 12 marks gone down the drain...


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    #49
    Undergod
    Registered Users Posts: 2,858 ✭✭✭Undergod


    No, that's always on the paper, every year, as is electronegativity.


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    #50
    Jayeire
    Closed Accounts Posts: 295 ✭✭Jayeire


    It's over! thats what I think :)

    I'm not gonna analyse what I got right/wrong now, I don't see the point... it can't be changed... so why upset myself :cool:

    Chem = done & dusted


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    #51
    Calorimeterman
    Closed Accounts Posts: 64 ✭✭Calorimeterman


    It was a nice paper, I can see most of you got the same answers as me, which is reassuring.

    I made a couple of niggly errors, but that's going to happen in every exam, I just hope they don't accumulate to more than 40 marks...

    I'm glad I did pH as an extra question, it was surprisingly easy (way easier than the organic experiment or even the general organic question).

    I also noticed that they were offering less marks for the same old stuff, like the structural formulae were only 3 marks each as opposed to 6 in previous years...

    Ah well, it's all over, until I do it in college next year...


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    #52
    clairehere
    Closed Accounts Posts: 8 ✭clairehere


    It went awfully bad for me!It was like my nightmare paper...


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    #53
    marus aureilous
    Closed Accounts Posts: 8 ✭marus aureilous


    okish paper didnt get that equilbrium not got da rest of it wasnt banking on it for q 1 wasnt da vinegar diluted 10 times so it shud hav been .90 waht ever instead no? dats wat i did otherwise gud paper b2 hopefully


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    #54
    tute08
    Closed Accounts Posts: 10 ✭tute08


    Fock....


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    #55
    JSK 252
    Registered Users Posts: 1,257 ✭✭✭JSK 252


    Im only in 5th year but looked at the titration question on the exampaper on the website:

    Va=22.73
    Ma=?
    Na=1
    Vb=25
    Mb=.10
    Nb=1

    22.73Ma = 2.5
    1 1

    22.73Ma = 2.5

    Ma = .109 mol/l

    CH3COOH = 60g ( relative atomic mass )

    60 x .109 = 6.54 g/l

    concentration of original sample in grams per litre ( dilution factor X 10 ) = 65.4 g/l

    w/v= g/100cm3

    65.4 g/1000cm3

    = 6.54 g/100cm3

    = 6.54% w/v

    Phenolphthalein colour change is from pink to colourless when the indicator is placed in the BASE in the conical flask and the titration is carried out.


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    #56
    JSK 252
    Registered Users Posts: 1,257 ✭✭✭JSK 252


    Thats was a bit of a **** alright to put that isomer question on the paper. A very genuine mistake for people not know that the first member of the alkene series has 2 CARBON ATOMS.

    Thats the SEC for you.


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    #57
    Parsley
    Closed Accounts Posts: 3,144 ✭✭✭Parsley


    They did say about two lines up that ethene was the first member.


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    #58
    JSK 252
    Registered Users Posts: 1,257 ✭✭✭JSK 252


    Parsley wrote: »
    They did say about two lines up that ethene was the first member.

    Well thats fair enough I suppose. I didnt see that but still I can agree that a stupid mistake like that can be made in an exam.


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    #59
    raah!
    Registered Users Posts: 2,629 ✭✭✭raah!


    They also said "any of the isomers" and there is only one isomer of propene. I remember just staring at it for ages thinking "why would they say that?".

    Still did it wrong though :D. No matter though, I did nine questions


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    #60
    Calorimeterman
    Closed Accounts Posts: 64 ✭✭Calorimeterman


    Hey, there were 12 marks going for it, maybe they'll give us marks for any tetrahedrally and planar atoms that we correctly circled?

    I dunno... hopefully... I'm glad I did pH as an extra question, it covered for that mistake at least!


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    #61
    IHATECHEMISTRY
    Closed Accounts Posts: 9 ✭IHATECHEMISTRY


    yesssssssssss...got butene riiight!! Actually guesssed it, so wooo hu
    luck on the day i suppose.
    Anyone find the organic questions trickier than usual????????????


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