Edexcel AS Chemistry Unit 2 Thread Watch

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manwithmidi
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#181
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#181
Group 7 will be the death of me :/.

Does anyone know whether we will be given data booklets?

One of my chem teachers seems to think we will but I'm not so sure he's right.
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dunnoaboutme
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#182
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(Original post by Phalange)
Chloride:
AgNO3 - WHITE PPT
then NH3 - soluble in dilute or conc NH3

organic solvent - pale green colour
water - pale green colour
room temp - green gas

Bromide:
AgNO3 - CREAM PPIT
then NH3 - soluble in ONLY conc NH3

organic solvent - orange-red
water - yellow orange colour
room temp - red-brown liquid

Iodide:
AgNO3 - YELLOW PPT
then NH3 - not soluble in any

organic solvent - pink-violet
water - brown
room temp - dark grey solid

You do not really need to add organic solvents because as far as I know AgNO3 + NH3 are okay.
cheers
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AGM
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#183
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(Original post by manwithmidi)
Group 7 will be the death of me :/.

Does anyone know whether we will be given data booklets?

One of my chem teachers seems to think we will but I'm not so sure he's right.
Everyone gets given a booklet, which importantly to us contains a periodic table and the different frequencies bonds make on IR absorption charts.
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Coke Or Pepsi
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#184
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I hate how vague everything is!!!
ARGH
AKA the colours of the halogens in different solutions i.e. in water and hexane and then like what you observe when you react it with SULPHURIC ACID CONC.


OMG I'm so panicking now - thanks tsr for making me panic!!
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Phalange
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#185
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#185
(Original post by manwithmidi)
Group 7 will be the death of me :/.

Does anyone know whether we will be given data booklets?

One of my chem teachers seems to think we will but I'm not so sure he's right.
If the data booklet contains IR spectra values, then yes, we could but I doubt it for anything else
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Narik
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#186
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#186
I feel as though I'm missing out on something. I'm going to sound cocky, but the hardest thing is learning those reactions and after that, you're pretty much sorted. You can lose like 30 marks and still get an A, so I don't get why people are so worried. I need to stress out over this exam, because I'm not doing anything. :facepalm2:
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SkyNinja
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#187
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(Original post by SK-mar)
ok sorry to nit pick at that titration but how are we supposed to find out moles of anything in that as we only have volumes given to us?? can you please give me an example of a question for this titration and answer it..
10.00cm3 of a sample of bleach was diluted into a 250cm3 with water. 25.0cm3 of this solution was pipetted into a flask. An excess of aqueous potassium iodide was then added to liberate iodine:
EQUATION 1: CL2(aq) + 2I-(aq)---->I2(aq)+2CL-(aq)
Titration of this solution required 23.2 cm3 of 0.100 mol dm-3 sodium thiosulphate.
EQUATION 2: 2 S2032- (aq) + I2 (aq) ---> 2 I- (aq) + S4062-

(A) calculate the concentration of chlorine bleach.
From the titration results, amount (in moles) of Na2S2O3 can be calculated:
n = c x v = 0.100 x 23.2/1000 = 0.00232 nol

(B) From the equation the amount (in moles) of CL2 can be determined:
from equation 2: 2 mol S2O32- reacts with 1 mol I2
0.00232 mol S2O32- reacts with 0.00232/2 mol I2= 0.00116 mol I2
From equation 1: 1 mol CL2 forms 1 mol I2, amount in mol of CL2 = 0.0016 mol

(C) The concentration in mol dm-3 of the diluted bleach solution can now be calculated by scaling 1000cm3:
25.0 cm3 of diluted bleach contains 0.00166 mol CL2
1 cm3 of diluted bleach contains 0.0016/25 mol CL2
1 dm3 of diluted bleach contains 0.0016/25 x 1000 = 0.0464 mol CL2

(D) Finally take into account the dilution with water from 10 cm3 to 250 cm3:
The original bleach was diluted by a factor of 250/10=25
concentration of CL2 in the bleach is 25 x 0.0464 = 1.16mol dm-3

I hope this helps, sorry i just realised that i only typed half the question in the other comment. I tryed my best to type the equations however if you have any problems understanding equation 2 with all the same size numbers the eq 2 is on this website:
http://usm.maine.edu/chy/manuals/116/text/RdxTi.html
i hopes this helped sorry if i did any typing errors, im quite worried about this exam so i have to revise alot If you have any questions just ask.
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Coke Or Pepsi
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#188
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(Original post by Narik)
I feel as though I'm missing out on something. I'm going to sound cocky, but the hardest thing is learning those reactions and after that, you're pretty much sorted. You can lose like 30 marks and still get an A, so I don't get why people are so worried. I need to stress out over this exam, because I'm not doing anything. :facepalm2:
Thing is i've been so relaxed all this time then I come on here and everyone's panicking it's making me panic and making me feel like I've not done enough I only need like a C to get an A in this exam...
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Rohit93
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#189
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Anyone got the specimen paper ? If there is one ?
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SkyNinja
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#190
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(Original post by Narik)
I feel as though I'm missing out on something. I'm going to sound cocky, but the hardest thing is learning those reactions and after that, you're pretty much sorted. You can lose like 30 marks and still get an A, so I don't get why people are so worried. I need to stress out over this exam, because I'm not doing anything. :facepalm2:
so your saying 50/80 is an A? , this is going to be one hard test lol.
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SkyNinja
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#191
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(Original post by Rohit93)
Anyone got the specimen paper ? If there is one ?
Rohit have you tryed looking? lol go on the edexcel website all the past papers are there including the specimen one.
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Coke Or Pepsi
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(Original post by SkyNinja)
so your saying 50/80 is an A? , this is going to be one hard test lol.
No! I meant, to get an A overall, I need a C grade in this paper which is like 60 or something UMS. Sorry should've worded it more clearly! :rolleyes:
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Narik
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#193
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#193
(Original post by SkyNinja)
so your saying 50/80 is an A? , this is going to be one hard test lol.
Yepp. Sometimes it's as low as 49/80 for an A. So I don't get why people are going so :woo:. It's like, relax...:cool:.

(Original post by Coke Or Pepsi)
-
Yeah I need 60 something UMS for an A. :facepalm2:
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Rohit93
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(Original post by Coke Or Pepsi)
No! I meant, to get an A overall, I need a C grade in this paper which is like 60 or something UMS. Sorry should've worded it more clearly! :rolleyes:
I only got a B in Unit 1 =[ i got 37/40 in the practical but dont know how much that is in UMS, what do you think i need to get an A? in this unit 2 test =/
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SkyNinja
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#195
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#195
how can i relax if i know the questions are going to be ultra tough lol
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Coke Or Pepsi
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(Original post by Narik)
Yepp. Sometimes it's as low as 49/80 for an A. So I don't get why people are going so :woo:. It's like, relax...:cool:.


Yeah I need 60 something UMS for an A. :facepalm2:
Yeah that's what I'm saying lols. It's making me proper panic! In the January module I got 64/80 raw and that was scaled up to 120/120 UMS!
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Coke Or Pepsi
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(Original post by Rohit93)
I only got a B in Unit 1 =[ i got 37/40 in the practical but dont know how much that is in UMS, what do you think i need to get an A? in this unit 2 test =/
To get an A you need to get an A but not necessarily a high A I think. I can calculate it for you but you need to give me your unit 1 ums score!
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Rohit93
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(Original post by Coke Or Pepsi)
To get an A you need to get an A but not necessarily a high A I think. I can calculate it for you but you need to give me your unit 1 ums score!
oh i got 87
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Coke Or Pepsi
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(Original post by Rohit93)
oh i got 87
You need 100 UMS
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Rohit93
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#200
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(Original post by Coke Or Pepsi)
You need 100 UMS
Oww maan lool thts gey -.-
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