Chemistry: Post your doubts here!

[6Astarstudent]

Thanks.. I didnt think it would get oxidised as well. ( the original OH group)
so basically organic product for CH2=CHCH2OH + hot KMnO4 = no organic product?
since first it becomes HCOOH + HOOCCOOH. HOOCCOOH gets oxidised to HCOOH as well. and HCOOH all get oxised to CO2 + H2O

 

[knowitall10]

Thanks.. I didnt think it would get oxidised as well. ( the original OH group)
so basically organic product for CH2=CHCH2OH + hot KMnO4 = no organic product?
since first it becomes HCOOH + HOOCCOOH. HOOCCOOH gets oxidised to HCOOH as well. and HCOOH all get oxised to CO2 + H2O

hmm.. good question.. i really don't know... u in AS?

 

[knowitall10]

Thanks.. I didnt think it would get oxidised as well. ( the original OH group)
so basically organic product for CH2=CHCH2OH + hot KMnO4 = no organic product?
since first it becomes HCOOH + HOOCCOOH. HOOCCOOH gets oxidised to HCOOH as well. and HCOOH all get oxised to CO2 + H2O

Go to the P1 and P2 Chem thread... they might answer it for you if you're in AS

 

[6Astarstudent]

Yeah Im AS, alright ill post there

 

[knowitall10]

Yeah Im AS, alright ill post there

Wait... don't post there yet.. i just checked it out; it been locked so u can't post before 24 hours. probably to prevent any paper discussion before it happens.

 

[raamish]

hey in qs 1 where there is no asking of the apparatus by the examiners and the y tell us to write on a 7 mark question should we include the drawing of the apparatus as well or we should just write the 7 marks of material

 

[knowitall10]

hey in qs 1 where there is no asking of the apparatus by the examiners and the y tell us to write on a 7 mark question should we include the drawing of the apparatus as well or we should just write the 7 marks of material

My teachers always told me that if you're good with writing the plan down, then write it. and count your points, if you think you wrote enough thats good but don't draw the apparatus if not required because your answer might be right, but any mistake in the apparatus you drew will send your marks down the drain.
but if you're sure of your drawing and you're sure that it explains everything, just add brief notes here and there and you're all good. But i wouldn't draw if i'm not sure of what they are asking me.

 

[xxfarhaxx]

i

hey in qs 1 where there is no asking of the apparatus by the examiners and the y tell us to write on a 7 mark question should we include the drawing of the apparatus as well or we should just write the 7 marks of material

i think its better to give a simple diagram as well as mention them in words.. we never know what the examiners want!

 

[raamish]

hey guys can anybody tell me qs 2e the reasoning for pt 3 to be anomalous point. i know the reasoning for pt 8

 

[hela]

Why is the power maximum when the load resistance is equal to the internal resistance? thank you

 

[MaxStudentALevel]

hey guys can anybody tell me qs 2e the reasoning for pt 3 to be anomalous point. i know the reasoning for pt 8

What paper and what version and what question?

 

[MaxStudentALevel]

Why is the power maximum when the load resistance is equal to the internal resistance? thank you

This was a CHEMISTRY thread last time I checked bro.

 

[raamish]

can anybody explain how to calculate 2f of j08 and 2e of j07. im confused as to how to calculate x from the data given. can somebdy tell me the whole procedure that we will use. I only drew one construction line in a middle of the graph

 

[trgirl]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_qp_52.pdf

Hi everyone my question is from paper5 i have an exam tomorrow. Can you help me how to find 1st question part d? I do not understand how i should estimate the volume and concentration and in part e how am i supposed to prepare ethanedioic acid?

 

[applepie1996]

I didnt get that part either... and i posted the question here.. but i forgot the answer someone gave

its okay

 

[Soldier313]

Aoa wr wb,
- Can someone please help me for qn 2, how do we know that the examiner wants the values of part 'bi' to 2 significnt figures, and for part 'bii', to 2 decimal places?
- Secondly, why is the ms stating that the ratio calculated in 'b ii' must be I:Zn and not the inverse, i mean i did it as Zn:I, but the ms clearly states not to do that:/
- And for part 'e' of the same qn, the reasons for the anomalies in the ms don't quite agree with my understanding, can someone please elaborate?

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_qp_51.pdf
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_ms_51.pdf

MaxStudentALevel xhizors and @ all other p5 candidates
Thanx a lot

 

[Thampi4]

yea.. when the question says "give step by step discrip. by...." then you describe only those points, that'll be sufficient. but if the question says "give a step by step descrip. including...." then i recommend you describe the full procedure INCLUDING the points the question gave you.

thanks mate

 

[MaxStudentALevel]

Aoa wr wb,
- Can someone please help me for qn 2, how do we know that the examiner wants the values of part 'bi' to 2 significnt figures, and for part 'bii', to 2 decimal places?
- Secondly, why is the ms stating that the ratio calculated in 'b ii' must be I:Zn and not the inverse, i mean i did it as Zn:I, but the ms clearly states not to do that:/
- And for part 'e' of the same qn, the reasons for the anomalies in the ms don't quite agree with my understanding, can someone please elaborate?

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_qp_51.pdf
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_ms_51.pdf

MaxStudentALevel xhizors and @ all other p5 candidates
Thanx a lot

FOR B) The values calculated should not be less than the values used to calculate! So for this, all readings are to 2 dp so the values used to calculate the mass of iodine are all to 2dp ours should be as well! The trick is always to do equal dp as readings UNLESS stated otherwise (like sometimes they say (3sf) specifically so follow that in that case!

-AS for the second part I'm slightly confused with that also! Can't seep to find a logical reason! xhizors ?

-I think the logical way here, rather the Intuitive way was to calculate I:Zn as we need an answer of 2 for that! Because I:Zn ratio would be 2 if exp showed its validity. That's the only logical reason I can think of!

-ANOMALIES: IF I:Zn ratio differs from the rest by a lot it is an anomalous result!
-If I:Zn is too high (meaning mass ofZn was too low) then means Zn must've been blown out of tube while heating!
-If I:Zn too low (meaning mass if Zn too high) maybe not dried enough!

Any other confusions?

 

[fatemakhan]

Could you explain the logic behind your answer?
I got 14.3g deposited.

----> According to my curve at 85degrees=40g per 100g so 20g per50g (SO 20g dissolved)
-----> Also same for 35 degrees = 11.5g per 100g so 5.7 per 50 (SO 5.7g dissolved)

MEANING initial mass dissolved -final mass dissolved = deposited solid.
----> 20-5.7 = 14.3g

CORRECT ME IF MY THINKING IS WRONG GUYS!!!

i think yours is right =/
even i dont know how to explain what i did there... i think to say i just took out % dec. in solubility and considered it to be the % dec in dissolved solid would be the right explanation...but then i shouldve stopped here ... and 14.8g wouldve been the ans according to me....
does that make any sense ? =/

 

[fatemakhan]

Hey I've got a question about this chem p5 you guys are talking about above ^
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_52.pdf
So for Q2 a) how did you calculate the solubility column?
Like was it just (mass of water) divided by (mass of solid) or something else?
Help would be greatly appreciated

multiply by 100 too!