Chemistry: Post your doubts here!

[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.

 

[..sacrifice4Revenge..]

btw,
the values of Kp and Kc are only affected by changes in temperature, right?

 

[SIstudy]

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)

Pls help me with these questions some one :/ :/

 

[SIstudy]

btw,
the values of Kp and Kc are only affected by changes in temperature, right?

yes

 

[princessnoor]

btw,
the values of Kp and Kc are only affected by changes in temperature, right?

yh

 

[GCE As and a level]

btw,
the values of Kp and Kc are only affected by changes in temperature, right?

Yes

 

[MiniSacBall]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s07_qp_1.pdf

Q9, Q29, Explain plz


http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s10_qp_11.pdf
Q13

Also, how does it hydrochloric acid behave as acid when it is added to NaCl,
And H2SO4 conc. is used for hydrolosis or dehydration, and what about NaOH,

I need urgent help please !!!