[mimx]

(Original post by n00b/)
You read from graph wrongly

I got 1 mole ------> 24l

? --------> 0.11l

?= 0.0046moles

0.0046 * 6.02*10^23 = 2.76*10^21

You're right, fixed. I didn't do this in the exam, honest

[mimx]

(Original post by n00b/)
I agree with all your answers except for 17 - i got A - anyone confirm or deny?

I got A in the exam too, I think you're right.

[deedee123]

(Original post by n00b/)
I agree with all your answers except for 17 - i got A - anyone confirm or deny?

I got 17A

[Maryam A]

(Original post by mimx)
Ok so final (subject to corrections ) latex'd/image solutions for the whole thing:


SECTION A:

1 - D
2 - C
3 - D
4 - C
5 - B
6 - D
7 - C
8 - B
9 - A
10 - C
11 - D
12 - B
13 - B
14 - C
15 - D
16 - B
17 - A
18 - A
19 - C
20 - A
21 - A
22 - B
23 - B
24 - A
25 - C
26 - D
27 - D
28 - C
29 -B
30 - A
31 - B
32 - D
33 - A
34 - C
35 - B


SECTION B:

1)a) carbon OR boron.

b) increasing nuclear charge / pulls electrons closer / similar.


2)a) to prevent loss of acid spray during effervescence (whilst allowing gas to escape).

b)i) 0.017 g s^-1

ii) 0.39 g


3)a) 0.125 moles

b) incomplete combustion / evaporation of methanol / heat loss to surroundings


4)a)

b)i) no effect

ii) 5.523 g

c)


5)a) 2.76375 x 10²¹

b)

c) one which is in a different state from the reactants


6)a)


b)i) 0.00147 mol l^-1

b)ii) van der waals etc


7)a) W=9 X=6 Y=2 Z=2

b) two small molecules join to create a larger one over a C=C double bond

c) Between an N attached to an H on one molecule to an H attached to an N on the other.


8)a) amide/peptide link

b)


c) Essential (amino acid)

d) Condenser of some sort e.g. wet paper towel around mouth of test tube.


9)a)i) 3-methylbutan-2-ol

ii)



9)a) Bromine water test.

b) octadec-9,12,15-trienoic acid

c) right hand bit / the head


10)a) the air

b) methyl methanoate

c) 70%


11)a) 4 BF3 + 3 NaBH4 -> 2 B2H6 + 3 NaBF4

b) -2168 kJ mol^-1

c) 143444 kJ


12)a) to allow the potato discs to adjust to the temperature of the solution

b) hydrogen peroxide

c) enzyme denatured


13)a) 1.89 g

b)i) exothermic

ii) slope down left to right, same as last curve

c) they deplete the ozone layer


14)a)i) 10^-5

ii) NH₄NO₃ dissolves into NH₄⁺ and NO₃^-

Water equilibrium already present: [wrote out water equilibrium]

NO₃^- forms a strong acid with H⁺ from water equilibrium, so remains disassociated.

But NH₄⁺ forms a weak alkali with the OH^- ions so forms the equilibrium: [wrote out weak alkali equilibrium]

This reduces concentration of OH^- ions and so the water equilibrium shifts right to compensate.

This causes an excess of H⁺ ions and hence, acidity.

b) products readily combustible or similar


15)a)i) to maintain a constant current

ii) time, current

b)i) products can be recycled back into step 1

ii)


16)a)


b) (2-)methylbutane

hi i thought that it was the enzyme which was allowed to adjust to the environment? Dunno?
Also for 8b) i though it was an amino acid so i put it down with an amine group and carboxylic acid group at each end? porbably wrong though
thanks so much for putting the answers up!

[EliotMacauley]

Cheers for posting those Multiple Choice answers.. seems I’ve done slightly better than I thought. Roughly 27/40 looks like? Not the end of the world!

[DragonWalnut157]

(Original post by mimx)
12 a) to allow the potato discs to adjust to the temperature of the solution

Is it not to adjust to the new pH, seeing as it was measuring the effects of pH and not temperature?

[mimx]

(Original post by Maryam A)
hi i thought that it was the enzyme which was allowed to adjust to the environment? Dunno?

Yeah, that's pretty much the same thing.

(Original post by Maryam A)
Also for 8b) i though it was an amino acid so i put it down with an amine group and carboxylic acid group at each end? porbably wrong though

Most of the draw this compound ones I actually just looked up the structures instead of working it out, and I think for that one I got what I put as the image so I think it's right.

[mimx]

(Original post by DragonWalnut157)
Is it not to adjust to the new pH, seeing as it was measuring the effects of pH and not temperature?

It's pH buffer solution so it should be neutral in pH though that may be a change from potato fluid or whatever. I pulled my answer off a PPA sheet but I think maybe a better answer is the general 'to let it adjust to the new conditions' as said.

[Maryam A]

(Original post by mimx)
Yeah, that's pretty much the same thing.




Most of the draw this compound ones I actually just looked up the structures instead of working it out, and I think for that one I got what I put as the image so I think it's right.

ok thanks!

[Tara I]

(Original post by deedee123)
I was close to tears in the exam thinking i was doing awful, but i appear to have done alright actually! I didn't even attempt to balance that equation, I can't get my head around them, but oh well! So annoyed about the last question, wrote pentane instead! hopefully get a wee half mark for that though

I wrote pentane, and I was talking about the fatty acid! That was unthinkable.

[Tara I]

(Original post by DragonWalnut157)
Is it not to adjust to the new pH, seeing as it was measuring the effects of pH and not temperature?

I really hope you're right, because that's what I wrote :P

[Kaaal]

Kinda wish i didn't mark my exam now... If the answers on here are right, then i got about 71%, which is gonna be either just scraping an A or just missing out.. gaaaah this is gonna bug me until i find out

[Aishah123]

Thanks for putting the answers up Maryam A!!

[Tara I]

How many marks was 15 b) ii) worth, anyone?

[Maryam A]

well... we all have to wait until august to find out for sure what we got. Good luck everyone!

[tomathon1]

Q7.c. what about the oxygen double bond to a H about it?

[Maryam A]

(Original post by Aishah123)
Thanks for putting the answers up Maryam A!!

It wasn't me! 'mimx' posted them thank you mimx

[dead101]

I found the multiple choice insanely difficult. It felt like there were all the same question just different numbers and I guessed quite a lot. Section B wasn't as bad. I'm aiming for a B but i doubt that. I hope the cut off marks are low

[Kaaal]

Can someone explain to me how 3.a) is 0.125 moles?

[KeithyDee]

Thanks for uploading the answers. I'm not quite sure how I did - looking at the Section B I think I have done fairly well but I can't remember Section A at all.

Does anyone have a link to the PDF of the paper? Or can someone kindly scan in the five multiple choice pages? I will buy you an Irn-Bru