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Chemistry P4| A2 only

L

larina

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kandelbiz said:
With aqueous solution containing halogens > halogens are always released at anode unless it is very dilute in which case you will obtain Oxygen. standard electrode potential value does not support this because there is something known as 'over voltage efect(which i think is out of syllabus scope)' so its better to remember that halogens are discharged at anode in most case(exception: solution is highy dilute)
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oooo i see! thanks!! (and also except fluorine! ;) )
 
L

larina

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princesskt said:
BOTH CAN BE USED I SEARCHED..........
CONC, HCL >80 C OR WITH aq OH.> 80 c as mntiond in ms
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no its either one of them
the following is from the mark scheme...
acid/H+/HCl etc. or alkali/OH–/NaOH NOT conc H2SO4 or any HNO3 [1]
heat/boil/reflux if temp given >90°C
 
saudha

saudha

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hw does the thermel stability of grp 2 nitrates and carbonates vary down the group?
 
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larina

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saudha said:
hw does the thermel stability of grp 2 nitrates and carbonates vary down the group?
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As we go down the grp, the thermal stability INCEASES cuz the size of the cation increases (anion size remains the same) so the degree of polarisation decreases..distortion of anion cloud decreases and therefore stability increases, i.e. more temp. is needed to break it up...
 
angelicsuccubus

angelicsuccubus

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hey have you guys gone through the application booklet? Has it got everything we need to know for section B or is it like too detailed and irrelevant?
 
saudha

saudha

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angelicsuccubus said:
hey have you guys gone through the application booklet? Has it got everything we need to know for section B or is it like too detailed and irrelevant?
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it has everything related to section B,the notes are too detailed ,just fine
 
angelicsuccubus

angelicsuccubus

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electrode potentials make no sense.. anyone got notes? I dont get what happens to the minus signs... sometimes they use them.. sometimes they dont -_-
 
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hm12

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oct nov 10 43 question 5 can anyone explain it? i am getting negative E knots but in the marking scheme they are all positive?
 
angelicsuccubus

angelicsuccubus

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hendrixgirl said:
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_41.pdf

question number 2 ) a) i) what is the order with respect to [H+] ??

COME ON IT ISNT HARD IM JUST CONFUSED PLEASE HELP ME!!
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okay, got it.. so to find the order with respect to [H+] -- compare experiment 1 and 2 because in experiment 1 and 3, [H+] and [CH3OH] remains the same while [CH3CHO] changes.

so [CH3CHO] goes from 0.2 to 0.25 its an increase by a factor of 1.25 (0.25/0.2)
What factor does [H+] increase by? also 1.25 (1.25/1).. hence the order is 1
 
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hendrixgirl

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angelicsuccubus said:
okay, got it.. so to find the order with respect to [H+] -- compare experiment 1 and 2 because in experiment 1 and 3, [H+] and [CH3OH] remains the same while [CH3CHO] changes.

so [CH3CHO] goes from 0.2 to 0.25 its an increase by a factor of 1.25 (0.25/0.2)
What factor does [H+] increase by? also 1.25 (1.25/1).. hence the order is 1
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what are you talking about? in 1 and 3 [H+] doesnt even change?
how do you find out its 1 like that?
 
angelicsuccubus

angelicsuccubus

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angelicsuccubus said:
okay, got it.. so to find the order with respect to [H+] -- compare experiment 1 and 2 because in experiment 1 and 3, [H+] and [CH3OH] remains the same while [CH3CHO] changes.

so [CH3CHO] goes from 0.2 to 0.25 its an increase by a factor of 1.25 (0.25/0.2)
What factor does [H+] increase by? also 1.25 (1.25/1).. hence the order is 1
Click to expand...
oh crap you're right.. I just looked at it again, there aren't any experiments where the other two concentrations are constant... maybe they round up? I donno.. sorry
 
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