The Official Summer 2011 IB Exams Discussion Thread Watch

vms
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#141
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#141
(Original post by daot)
hi guys, i just wanted to ask a quick question. i made a silly mistake on my hl math paper (amongst many others), but this one involved not answering each new question on a separate page like they requested. i'm hoping that this isn't an atrocious mistake that'll destroy my entire section B. does anyone know if they'll take this into account when marking? or if it's because they mark section B questions separately? because then i'm really screwed.
no worries I did that too, you'll be fine
a lot of people in my year ignored that rule doing the paper so they're presumably not going to fail us all
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Commando3200
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#142
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#142
(Original post by vms)
salutations, any chemists willing to explain to me the answer of this question por favor?

23. Consider the following equilibria in 0.10 moldm?3 carbonic acid.
H2CO3 (aq) <---> H+ (aq)+HCO3 - (aq)
HCO3 - (aq) H+ (aq) + CO3 2- (aq)

Which species is present in the highest concentration?
Do you mean:

H2CO3 (aq) <---> H+ (aq)+HCO3 - (aq)
HCO3 - (aq) <---> H+ (aq) + CO3 2- (aq)

Are they asking specifically for the comparison between H2CO3 and HCO3, or a comparison within the equilibrium?

HCO3 - (aq) <---> H+ (aq) + CO3 2- (aq) <--- This is impossible by the way. CO3 is a 2- charge, therefore it must be H2CO3 as the first equation.

Care to elaborate?
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sayyafordae
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#143
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#143
(Original post by Commando3200)
Do you mean:

H2CO3 (aq) <---> H+ (aq)+HCO3 - (aq)
HCO3 - (aq) <---> H+ (aq) + CO3 2- (aq)

Are they asking specifically for the comparison between H2CO3 and HCO3, or a comparison within the equilibrium?

HCO3 - (aq) <---> H+ (aq) + CO3 2- (aq) <--- This is impossible by the way. CO3 is a 2- charge, therefore it must be H2CO3 as the first equation.

Care to elaborate?

Just did this question. It was a multiple guess where the options were:

A. H2CO3(aq)
B. H+ (aq)
C. HCO3 1- (aq)
D. CO3 2- (aq)

In the actual question it was indeed written as HCO3 but i do think they meant H2CO3 as in the response. The answer (according to IB) is A.

Anyone able to explain this answer?? :/
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vms
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#144
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#144
this article is the story of my life

http://www.timesonline.co.uk/tol/new...cle4321718.ece
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omegah
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#145
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#145
(Original post by daot)
hi guys, i just wanted to ask a quick question. i made a silly mistake on my hl math paper (amongst many others), but this one involved not answering each new question on a separate page like they requested. i'm hoping that this isn't an atrocious mistake that'll destroy my entire section B. does anyone know if they'll take this into account when marking? or if it's because they mark section B questions separately? because then i'm really screwed.
I think they ask people to do that for ease of marking, but I don't think it will affect your grade... i.e. if you have clearly labelled where each question begins, I don't think they'll just miss out the parts that are on the same page as another. I'm no expert, but I think it should be fine
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Raikyure
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#146
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#146
It was nice to write chemistry directly onto the answer sheet without having to use extra sheets I like answer boxes.
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Commando3200
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#147
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#147
(Original post by sayyafordae)
Just did this question. It was a multiple guess where the options were:

A. H2CO3(aq)
B. H+ (aq)
C. HCO3 1- (aq)
D. CO3 2- (aq)

In the actual question it was indeed written as HCO3 but i do think they meant H2CO3 as in the response. The answer (according to IB) is A.

Anyone able to explain this answer?? :/
Hmm, makes sense. Since we know that H2CO3 is a weak acid, it doesn't dissociate to a great extent. This rules out possibilities B and D. Now, since we know that H2CO3 exists naturally as carbonic acid, we should thus rule out the HCO3 1- as it doesn't exist naturally. Also, I'd assume that it is easier for an H2CO3 to donate a proton than it would be for HCO3 1-. Also, it appears as though the H2CO3 is what leads to the presence of the HCO3 1- ion, and since we already know that it doesn't dissociate to a great extent due to the fact that it is a weak acid, the answer must therefore be A.

(Original post by Raikyure)
It was nice to write chemistry directly onto the answer sheet without having to use extra sheets I like answer boxes.
I found them quite helpful too! However, it made it slightly annoying to pick a Section B question as we couldn't see the whole question and thus didn't have a complete view of what they were asking. It made it more difficult to find the easiest ones to answer.

Until now, however, I like answer boxes! Good luck with Paper 3 everyone (Biochem and Medicine Drugs here!). Bio HL gives me the natural advantage to my Physics HL compatriots in my class in this respect .
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meganeira
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#148
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#148
Anyone doing Physics please check this out and contribute please?
http://www.thestudentroom.co.uk/show....php?t=1633589
Thanks.
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tgardnermarx93
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#149
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#149
(Original post by Raikyure)
It was nice to write chemistry directly onto the answer sheet without having to use extra sheets I like answer boxes.

oh wow I know right?! I didn't use the paper and it was so nice to write in the boxes. I did get worried when I wrote out of the boxes though and had a panic moment where I asked if it would be scanned out but I'm sure it's all cool - it better be :P
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moneyballs2
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#150
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#150
Does anybody wish to be included in my will?
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moneyballs2
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#151
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#151
Staying up all night to revise. Good idea or bad idea?

I'll let you know in about 12 hours.

I expect the hallucinations to start in a little while.
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JamesTHRASH
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#152
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#152
Ok Well here's my summary (TZ2)

1. English A1 HL paper 1 --> not bad, poem was ok, but i never know exactly how i've done for commentaries
2. Math SL --> REALLY GOOD, besides q10 on paper 2, god damn trapezium stuffs, i think i lost half mark on a 17 mark Q
3. Music SL ---> Worst exam ever :|
4. Chemistry HL --> Paper 1 was ok, Paper 2 section a was horrific, but sec.B was good. Paper 3 was eh, suck at human bio though.
5. English A1 Paper 2 HL ---> Meh, just ok

Any thoughts?
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JamesTHRASH
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#153
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#153
(Original post by tgardnermarx93)
oh wow I know right?! I didn't use the paper and it was so nice to write in the boxes. I did get worried when I wrote out of the boxes though and had a panic moment where I asked if it would be scanned out but I'm sure it's all cool - it better be :P
Errr sorry to break this to you, but anything not in the box won't be marked unless it's on seperate answer paper.
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katechoi
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#154
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#154
(Original post by JamesTHRASH)
Errr sorry to break this to you, but anything not in the box won't be marked unless it's on seperate answer paper.
how do you know this for sure?
****.........
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SPRINGFINGER1
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#155
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#155
(Original post by JamesTHRASH)
Errr sorry to break this to you, but anything not in the box won't be marked unless it's on seperate answer paper.
this is wrong. our ib coordinator said that it was fine to exceed the boxes, provided that you don't exceed the barcode at the end. obviously when its scanned the examiners will see the whole sheet of paper and mark what is relevant.
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writer27
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#156
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#156
Argh Physics tomorrow :/ It will be a miracle if I pass.
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katechoi
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#157
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#157
(Original post by SPRINGFINGER1)
this is wrong. our ib coordinator said that it was fine to exceed the boxes, provided that you don't exceed the barcode at the end. obviously when its scanned the examiners will see the whole sheet of paper and mark what is relevant.
i really hope you are right
for both chem and geography papers i exceeded the boxes but within the barcode
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Raikyure
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#158
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#158
Okay, so how do I turn 2 years of no physics into a 5-6 in physics SL by tomorrow? I have some 18 hours and a A1 paper 1 in between :/
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Helena'sIMMORTAL
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#159
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#159
RIGHT KILL ME now !! that papert 2 higher level english was effin hard!! I hate paper 2 hopefully because its only 20% doesn't make my grade fall ... too low that is urg
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000
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#160
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#160
careful, it hasn't been 24 hours yet so you can't talk about any exams that were today
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