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.
clydeshen411
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#1541
the international science edexcel papers this year is different from the one in uk! my offer requires an A in chemistry so i need to get 77% (only 83% in AS) this year... but my unit 4 was horrible, it was a difficult paper and I've lost like 5 marks by stupid mistakes, not even sure if i can get an A for that unit feel like im gonna miss my offer
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AtomicMan
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(Original post by lordmackery)
What does everybody want/need in this paper then?
Need 96 for an A*

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clydeshen411
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(Original post by JRP95)
Hmm I'd take a gamble and not bother then, a big steam distillation question already came up a couple of years ago so they'll probably do something on recrystallisation/reflux/fractional distillation.

Also we don't need to know about all that stuff you said after the steam distillation?
Lol there are questions on recrystallisation/reflux/fractional distillation almost every year in unit 6b, the international alternative paper
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senz72
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(Original post by lordmackery)
What does everybody want/need in this paper then?
I need a B in chemistry which should be achievable I hope. I need 49 UMS. Want to push for an A but it seems a bit distant due to exam stress and lack of revision. Oh what have I done...

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DrewYouTwo
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So practice questions guys.

Explain how Chomium hydroxide complex ions are amphoteric?
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Knoyle quiah
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Can someone please explain what is happening from CuI to F and from F to C by shaking and how to get from B to CuS04 again
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posthumus
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Just did my first past paper today and I found it outrageously difficult (January 2011) :/

I understood most questions after going through the mark scheme and referring back to my book, however there was a question 15iv ... which required me to know about "azo-dyes" ??!!

That made no sense to me and it was worth 5 marks... along with another 5 marker which was the final question. I didn't have a clue what section C was all about

This unit is stupendously difficult!


(Original post by DrewYouTwo)
So practice questions guys.

Explain how Chomium hydroxide complex ions are amphoteric?
They can be further deprotonated to form water or they can react with H+ to form H2O ligands in the complex?
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Knoyle quiah
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how is it oxidised when reacting with iodine??? surely its reduced ??
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posthumus
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(Original post by Knoyle quiah)
how is it oxidised when reacting with iodine??? surely its reduced ??
The sulfur in thiosfulate ion is oxidized by the iodine... one clue is that the iodine has been reduced from 0 to -1 state... therefore thiosulfate must have been oxidized! Since it's a redox reaction...

S2O3^2- .... the oxidizing state of sulfate here is:

Well oxygen -2 x 3 = -6.... there's already -2 charge.... -4 ... therefore each of two sulfur ions must be in the +2 state

then in S4O6^2- .... -2 x 6= -12 ... there's already -2 charge..... -10 .... therefore each of the 4 sulfur ions must be in the +2.5 state... and increase in oxidation number (by 0.5) means it has been oxidized
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jojo1616
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Can anyone explain this question ?thx
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Knoyle quiah
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(Original post by jojo1616)
Can anyone explain this question ?thx
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do you have george facer book?? page 224
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Knoyle quiah
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(Original post by posthumus)
The sulfur in thiosfulate ion is oxidized by the iodine... one clue is that the iodine has been reduced from 0 to -1 state... therefore thiosulfate must have been oxidized! Since it's a redox reaction...

S2O3^2- .... the oxidizing state of sulfate here is:

Well oxygen -2 x 3 = -6.... there's already -2 charge.... -4 ... therefore each of two sulfur ions must be in the +2 state

then in S4O6^2- .... -2 x 6= -12 ... there's already -2 charge..... -10 .... therefore each of the 4 sulfur ions must be in the +2.5 state... and increase in oxidation number (by 0.5) means it has been oxidized
Thank you forgot about that iodine being reduced
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posthumus
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(Original post by jojo1616)
Can anyone explain this question ?thx
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I don't understand this completely but it needs to have 2 Cl- atoms ionically "attached" to it.... to give 2 moles of AgCl

Therefore the charge must be +2 on the complex.... but yh like Knoyle suggested, best to refer to the George Facer book
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Knoyle quiah
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are people learning how to make Terylene, Kevlar, and nylon 6,6 from scratch including knowing the monomers??? its on the spec but do we need to know how to make from scratch?
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Bord3r
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(Original post by jojo1616)
Can anyone explain this question ?thx
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Think of it in terms of ratios. In every 1 molecule of the complex there are three chlorines.
In every molecule of AgCl there is one chlorine.
However because there's double the number of moles of AgCl compared to the complex, there are two chlorines going to AgCl for every molecule of complex.
This leaves one Chlorine which must remain in the complex, thus the answer is C.
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LeaX
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if we were asked to show how zinc hydroxide is amphoteric by equations are these correct:

(Zn(OH)2(H2O)4] + H+ --> [Zn(OH)(H2O)5]+1
[Zn(OH)2(H2O)4] + OH- --> [Zn(OH)3(H2O)3]-1 +H2O
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freakynerdlol
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How much of units 1,2 and 4 do we need to know for this exam?

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JRP95
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(Original post by freakynerdlol)
How much of units 1,2 and 4 do we need to know for this exam?

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All organic reactions are expected to be known. (so that's Like free radical elec addition even elimination)
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Knoyle quiah
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what is steam distillation actually used for?? i understand how it works but dont know the purpose for it
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JRP95
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(Original post by Knoyle quiah)
what is steam distillation actually used for?? i understand how it works but dont know the purpose for it
If the boiling temp of the mixture you're distilling is so High that it begins to decompose you pass steam into it to lower the boiling temp so it distills at a lower temp.
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