Chemistry: Post your doubts here!

[..sacrifice4Revenge..]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_11.pdf

q9
why wont we use the moles of Fe+3 also, like
why wont it be
0.56^2/0.44^2

 

[Suchal Riaz]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w03_qp_1.pdf
Q40. Statement 2?
Suchal Riaz

C=O
|
O
it is ester group. when it will hydrolyse in NaOH it will make --CO2- Na+

 

[princessnoor]

have you any idea of what are you saying?
what do you mean by this:

ZaqZainab said: ↑
Listen if it has HIGH ionisation energry it mean it DOESNOT give off electrons easily and there will be less electrons in the lattice and if less electrons the pull wont be that grea and so the melting point will be low easy to melt
thn u tell me

 

[ZaqZainab]

ionisation energy have no relationship with melting/boiling point. It has been confirmed by Jim Clarke.

a little proof eh?
http://www.yoIutube.com/watch?v=tBS_i6vnI5E <---- my source
remove the 'I'

 

[Kamihus]

C=O
|
O
it is ester group. when it will hydrolyse in NaOH it will make --CO2- Na+

Then why is this statement WRONG?

 

[ZaqZainab]

you are such a liar. you always solve all doubts and pretend like you know nothing

excuse me i know stuffs i am not that dumb i have doubts too just cause i can solve people doubts doesnt mean i know everything as the person said i can solve everything no that is wrong
and even if i could All praise to God i don't have pride

 

[Suchal Riaz]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_11.pdf

q9
why wont we use the moles of Fe+3 also, like
why wont it be
0.56^2/0.44^2

there are 0.44 mol of Ag+ so there are 0.44 mol of Fe2+
it means out of 1 mol o.44 remain, rest of them have been converted into Ag and Fe3+
so there are 1-0.44=0.56 mol of Fe3+ and 0.56 mol of Ag
Kc=0.56*0.56 / 0.44*0.44 = 1.62

 

[SIstudy]

can you just say what is confusing you in each question to make it easy for us to answer?

oh okay
in Q37 why the first statement is correct? I mean the empirical formula has 1 atom of O, so there must be aldehyde :/

in Q26 idk wht im doin wrond I tried it many times, but my answer isn't in the options :$ :/

in Q9 I coul make out tht glucose and fructose are structural isomers so option A and C is ruled out but cant understand how osmotic pressure is affected

Q29 don't get it at all :/

Btw its http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_12.pdf
Q37 (D)
Q26 (B)
Q9 (D)
Q29 (D)
Q35 (B)
Q40 (A)

 

[Jelleh Belleh]

Something I think might be worth mentioning, in case some of you don't already know:
In an organic question, if you see LiAlH4 being used, know that it's a reducing agent, just like NaBH4. This is another one of the additions to the syllabus.

 

[..sacrifice4Revenge..]

there are 0.44 mol of Ag+ so there are 0.44 mol of Fe2+
it means out of 1 mol o.44 remain, rest of them have been converted into Ag and Fe3+
so there are 1-0.44=0.56 mol of Fe3+ and 0.56 mol of Ag
Kc=0.56*0.56 / 0.44*0.44 = 1.62

thats precisely what i did
but ans is D, 2.89. :/
it is obtained if we solve
0.56/0.44*0.44
but thats incorrect

 

[Kamihus]

Something I think might be worth mentioning, in case some of you don't already know:
In an organic question, if you see LiAlH4 being used, know that it's a reducing agent, just like NaBH4. This is another one of the additions to the syllabus.

Also, H2 reduces an aldehyde to alcohol.

 

[_Ahmad]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w10_qp_11.pdf

Q7

 

[..sacrifice4Revenge..]

hope you guys know it already

last 10mcqs, by checking these you can simply arrive at the answer,saves time..
if 1 is incorrect. Answer is C
if 2 is incorrect, ans is D
if 3 is incorrect, ans is B
and if all are correct, A it is

 

[Suchal Riaz]

Then why is this statement WRONG?

omg i am sorry. it was distilled. it means that the dissolved salts will be separated.

 

[princessnoor]

there are 0.44 mol of Ag+ so there are 0.44 mol of Fe2+
it means out of 1 mol o.44 remain, rest of them have been converted into Ag and Fe3+
so there are 1-0.44=0.56 mol of Fe3+ and 0.56 mol of Ag
Kc=0.56*0.56 / 0.44*0.44 = 1.62

hey i have a question
in an experiment b mol of HI were put into a sealed vessel under pressure p.
ateqilibrium ,x mol of HI had dissociated
2HI--- H2 +I2
now tell how its answer is x2/4(b-x)2
i dont get how the 4 came

 

[Suchal Riaz]

thats precisely what i did
but ans is D, 2.89. :/
it is obtained if we solve
0.56/0.44*0.44
but thats incorrect

it is a bad day isn't it. Ag is solid. how can we find it's concentration?
sorry for that. Ag is solid. we don't consider solids

 

[Kamihus]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_11.pdf

Q7

1 is 109, tetrahedral arrangement.
2 is 120 as three bond pairs.
3 is 104 as two bond pairs and 2 lone pairs.

 

[..sacrifice4Revenge..]

it is a bad day isn't it. Ag is solid. how can we find it's concentration?
sorry for that. Ag is solid. we don't consider solids

omg, how could I have missed this.
*facepalm*
thanks bro!

 

[26697luj]

how is the bond energy in graphite stronger than that in diamond?:/

 

[Kamihus]

http://papers.xtremepapers.com/CIE/...AS Level/Chemistry (9701)/9701_w12_qp_13.pdf\
Q26 Just tell me what are the intermediates.