Edexcel Chemistry A2 Unit 5 ~ Wednesday 19th June 2013 (Now Closed) Watch

Poll: How pumped up are you for this exam?-(warning)-(bad jokes arene this poll!)
"Titanium-I'm not going to corrode (even at high temperatures)" (A*) (22)
16.67%
"Benzene's my middle name, give me the paper in a week and I'll ace it!" (A) (27)
20.45%
"Yeah, I'm fairly electrophillic (positively charged) about the exam" (B) (27)
20.45%
"I'm in the middle of the salt bridge, but I will pass-eventually" (C) (21)
15.91%
"I'm feeling rather electroNegative about this exam" (D) (18)
13.64%
"Benzene, what's that?" (E) (6)
4.55%
"Chemistry, what's that?" (F) (11)
8.33%
This discussion is closed.
bubblegummer
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#1761
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#1761
(Original post by I Hate Edexcel)
I don't understand how they got the answer to the last question on Section B in this paper? Did anyone else manage to do it?

Paper: http://www.edexcel.com/migrationdocu...e_20120619.pdf

Markscheme:http://www.edexcel.com/migrationdocu...s_20120816.pdf
X is a dipeptide (when two monomers of amino acid join together). It is refluxed so that it can be hydrolysed to form 2 amino acid. HCL acts as a catalyst
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Inspire12
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#1762
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#1762
hii can anyone explain the last part of the titration q in jan 2013? to get the percentage of the ascorbic acid why do they divide it by 2?????
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sounique
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Can someone please explain 15d for me please? June 2012. Need I say, Unit 5?

Looking at the summary for that reaction, I would say the answer is Potassium permanganate, in acid solution. I don't know where the mark scheme has got: "Sodium Hydroxide and a Manganese salt" from?

Thanks!
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Dolphino
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#1764
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#1764
Hey guys what would be the systematic name of paracetamol? Perhaps n phenol ethanamide
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sounique
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#1765
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#1765
(Original post by Inspire12)
hii can anyone explain the last part of the titration q in jan 2013? to get the percentage of the ascorbic acid why do they divide it by 2?????
0.5g x 4 = 2
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Killer_94
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(Original post by Dolphino)
Hey guys what would be the systematic name of paracetamol? Perhaps n phenol ethanamide
yeah it is phenyl ethanamide
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AtomicMan
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#1767
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#1767
Is Manganese in the +7 oxidation state violet or colourless?
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orange94
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#1768
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#1768
(Original post by Hellz_Bellz!)
I keep getting As in the past papers I'm doing... but the real thing is always so much harder than the past ones :cry2:

By the way, do we need to know all the reactions from AS? Like how to convert alkenes to halogenoalkanes and all that crap?
We need to know everything it's Synoptics so Any reaction can creep up on the sly


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Dolphino
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#1769
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#1769
(Original post by AtomicMan)
Is Manganese in the +7 oxidation state violet or colourless?
Violet. It's colourless in +2 state
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sounique
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#1770
(Original post by AtomicMan)
Is Manganese in the +7 oxidation state violet or colourless?
Violet. eg KMnO4 - purple. Mn 2+ is colourless (although pale pink in concentrated solution)
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sounique
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#1771
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Can someone please please explain Q16 Jan 2012! How is Br2 acidic?!
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orange94
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#1772
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#1772
(Original post by Inspire12)
hii can anyone explain the last part of the titration q in jan 2013? to get the percentage of the ascorbic acid why do they divide it by 2?????
15 iii) or 15iv)



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I Hate Edexcel
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#1773
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#1773
(Original post by bubblegummer)
X is a dipeptide (when two monomers of amino acid join together). It is refluxed so that it can be hydrolysed to form 2 amino acid. HCL acts as a catalyst
Ohhh okay, thank you! I thought polypeptides were hydrolysed by dilute acid... hmmm. Can they be hydrolysed with alkali or not?
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Piravinthan
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#1774
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how to balance reactions in fuel cells
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Bubblezzzz
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(Original post by LeaX)
Do you know if that is the only method of separation that we'll need to know about? If not, do we still follow those steps for any separation or does it differ depending on the mixture we're trying to separate? My book doesn't mention any of this.
Hey sorry for late reply, basically, in the exam I am hoping they will give context, so it will be much easier to see what they want, but there are normally two methods of extraction, depending on whether it is stable or unstable. In the case of being unstable organic, you must use steam distillation, followed by the standard drying procedure i.e. run of aqueous layer and add anhydrous salts. Other wise, if its stable, you can just distill it off, or if you know it is far more soluble in a certain solvent, whereas other substances in the same solution won't be, then you can use solvent extraction.
Hope this makes sense? x
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Bubblezzzz
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#1776
(Original post by sounique)
Can someone please explain 15d for me please? June 2012. Need I say, Unit 5?

Looking at the summary for that reaction, I would say the answer is Potassium permanganate, in acid solution. I don't know where the mark scheme has got: "Sodium Hydroxide and a Manganese salt" from?

Thanks!
Basically, any manganese salt in solution will form a complex ion with water ligands. Then if you add sodium hydroxide or even ammonia (any base) it will deprotonate it to the corresponding manganese hydroxide for which its solid (neutral complex) form can be written as Mn(OH)2 or Mn(H20)4(OH)2

You don't need to refer to summary for this

Hope that makes sense
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sounique
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(Original post by Bubblezzzz)
Basically, any manganese salt in solution will form a complex ion with water ligands. Then if you add sodium hydroxide or even ammonia (any base) it will deprotonate it to the corresponding manganese hydroxide for which its solid (neutral complex) form can be written as Mn(OH)2 or Mn(H20)4(OH)2

You don't need to refer to summary for this

Hope that makes sense
Perfect. Thanks.
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kabOOmm
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#1778
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#1778
what is solvent extraction!??
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LeaX
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#1779
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(Original post by Bubblezzzz)
Hey sorry for late reply, basically, in the exam I am hoping they will give context, so it will be much easier to see what they want, but there are normally two methods of extraction, depending on whether it is stable or unstable. In the case of being unstable organic, you must use steam distillation, followed by the standard drying procedure i.e. run of aqueous layer and add anhydrous salts. Other wise, if its stable, you can just distill it off, or if you know it is far more soluble in a certain solvent, whereas other substances in the same solution won't be, then you can use solvent extraction.
Hope this makes sense? x
thank you but i'm having a really hard time understanding this topic. my book mentions absolutely nothing on this. it tells me how to separate solids (recrystalisation) but not liquids. how does separation differ for aqueous and organic liquids? what is solvent extraction?
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randyaloul
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#1780
(Original post by sounique)
Wait what?! I just thought that Cr H20 6 is green! As it's in an aqueous solution and therefore ligand exchange has taken place?!!

Thanks for the rest
Before ligand exchange has taken place it's violet, after/if it takes place it becomes green
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