Chemistry: Post your doubts here!

[Es Jay]

I think
Warrior66 gave the ryt answers buy still can u confirm it?? and yeah which paper is this?

oct/nov 02

 

[Es Jay]

1. A and B and C
2. C and E (I thought this one was E only though)
3. E
4. C
5. C and D
6. E

Here's the marking scheme

thankyou so much!!
i was sure the secomd one was C only...lol
where did u get the ms frm? :/
and why cant A, B and D also be the answers for the last one?...they could replace the H atom and the -OH group ryte?

 

[daredevil]

Here are all the Important Chemistry Definitions for AS
i compiled them for quick revision because i always forget the statements of the laws and the definitions even though i have the concept.... so if anyone else has the same problem u can take help from this....
Please Pray for all of us appearing in the CIE this year.... if u pray for others the Angels pray for you Best of Luck =)

 

[daredevil]

Here is a checklist of all [i hope ] the organic reactions of AS
if any reactions are missing please tell me too I have a series of mnemonics to learn them too but its kind of a long story if u still want them then inbox me
Best of Luck

 

[A star]

Here are all the Important Chemistry Definitions for AS
i compiled them for quick revision because i always forget the statements of the laws and the definitions even though i have the concept.... so if anyone else has the same problem u can take help from this....
Please Pray for all of us appearing in the CIE this year.... if u pray for others the Angels pray for you Best of Luck =)

Here is a checklist of all [i hope ] the organic reactions of AS
if any reactions are missing please tell me too I have a series of mnemonics to learn them too but its kind of a long story if u still want them then inbox me
Best of Luck

cool

 

[A star]

heres a list which links up all organic reactions
https://skydrive.live.com/view.aspx?resid=AD7CCA97726D5367!609&app=Word&authkey=!AOrbkXaV2yJ3QJk

 

[daredevil]

cool

thanks ^_^

 

[A star]

thanks ^_^

welcome

 

[Amy Bloom]

PhyZac
I made it roughly: you add the labellings + other things.
I dunno how you draw the syringe so i left it as a box
I hope u understand it.

 

[hela]

when you make titration can we start with 50cm3 as an initial reading for each rough titration
in the MS it is written that do not give marks if start with 50cm3

 

[hela]

when you make titration can we start with 50cm3 as an initial reading for each rough titration
in the MS it is written that do not give marks if start with 50cm3

 

[hela]

when you make titration can we start with 50cm3 as an initial reading for each rough titration
in the MS it is written that do not give marks if start with 50cm3

 

[hela]

when you make titration can we start with 50cm3 as an initial reading for each rough titration
in the MS it is written that do not give marks if start with 50cm3

 

[Alice123]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_qp_22.pdf
Q3 a... please help.. y wud we react NaBr with H2SO4??

 

[raamish]

s02 qp: http://www.freeexampapers.com/index...evel/Chemistry/CIE/2002 Jun/9701_s02_qp_4.pdf
s02 ms: http://www.freeexampapers.com/index...evel/Chemistry/CIE/2002 Jun/9701_s02_ms_4.pdf

In qs 2a can somebdy tell me why the volume of Naoh taken is constant. Is it used in someway in the calculation of rate of rxn?

 

[Razo513]

Jazak'Allahum Khairan!!
btw in q 26..you said that ketones can be oxidised by acidified dichromate? I don't think that's right, is it?

ive got my notes mixed sorry :$ they dont only aldehydes change color from orange to green

 

[A star]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_22.pdf
Q3 a... please help.. y wud we react NaBr with H2SO4??

.
Now step by step explanation the only inorganic reactants NaBr and H2O and H2SO4. now neither Na compounds nor acids under go hydrolyses so for first stage the only reaction possible will be one given below
thenmove on to step 2 the HBr formed will react with the alcohol to form 1 bromobutane sulphuric acid i think catalysis the reaction
reactions
step1 NaBr(aq) +H2SO4(l)=NaHSO4(aq) + HBr(aq)
step2 HBr(aq) +CH3CH2CH2CH2OH =CH3CH2CH2CH2BR + H2O

 

[A star]

just seen the ms where does the acid come from arent we supposed to write seperate reactions for both stages

 

[Warrior66]

ive got my notes mixed sorry :$ they dont only aldehydes change color from orange to green

it's okay..no prob!

 

[Alice123]

.
Now step by step explanation the only inorganic reactants NaBr and H2O and H2SO4. now neither Na compounds nor acids under go hydrolyses so for first stage the only reaction possible will be one given below
thenmove on to step 2 the HBr formed will react with the alcohol to form 1 bromobutane sulphuric acid i think catalysis the reaction
reactions
step1 NaBr(aq) +H2SO4(l)=NaHSO4(aq) + HBr(aq)
step2 HBr(aq) +CH3CH2CH2CH2OH =CH3CH2CH2CH2BR + H2O

sulfuric acid is not present in the first stage Im soooooo confused so NaBr is supposed to react with water