Chemistry: Post your doubts here!

[saffe]

Two equilibria are shown below.

reaction I 2X2(g) + Y2(g) 2X2Y(g)
reaction II X2Y(g) X2(g) + )g( 2
1Y 2

The numerical value of Kc for reaction I is 2.

Under the same conditions, what is the numerical value of Kc for reaction II?
Answer is 1 over square root 2

 

[saffe]

the question is in the picture too

 

[MYLORD]

guys any last tips ?????!!!!

 

[GCE As and a level]

guys any last tips ?????!!!!

GO and SLEEP
Give ur self a break
BEST OF LUCK

 

[AhsanAfzal]

• guys any last tips ?????!!!!

  
  Lets pray for each other and ace the test with the help of Allah !!!
  

 

[..sacrifice4Revenge..]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_11.pdf
Q6
q11
Q17
q21
Q24
Q26
Q38

6- use PV=nRT to calculate number of moles
multiply the moles with Mr of Ammonia

q11- A, since if u divide the Enthalpy with N u will get of a single X-Y bond.
q17-calculate moles from PV=nRT
divide the mass by moles to get Mr and check against periodic table
21-D, since if you add C2H5, there will be two of them one one side, two C2H5 on the second Carbon and so no cis-trans.
24-c, cz u need to break the double bond and insert a OH on the second carbon which would be oxidised to ketone in the next step.
26-c, cz u need to remove a chlorine from one carbon and that same carbon has to be a radical
38-1 is correct, so is 2., basics. 3 is not because Alcohols dont undertake such substitution to form halogenoalkane

 

[..sacrifice4Revenge..]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_11.pdf
Q19 H3PO4 is weak acid, then why is the answer A?

weak acid is the organic acid for now. or the bronsted lowry thingy..

 

[kingo44]

iam living coz of chemistry give me a hell ya

 

[dumb human]

i recently scored 40/40 in 31 minutes(physics paper) and then 39/40 in 41 minutes(chemistry)
when i started doing papers i was at 27. the marks increased with practice till maximum of 36/40. with more and more practice and if only i am totally awake when doing paper i score 38+ otherwise 37 is an average.

Chemistry June 2013, Paper 1_2 Question 31?? y A?

 

[..sacrifice4Revenge..]

Good night people!
and All the best for tomorrow(today i mean, 5hrs to go for me )
Ace it!

 

[kingo44]

hhaaahhaaha ya roight know this people iam aliveeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

 

[..sacrifice4Revenge..]

Chemistry June 2013, Paper 1_2 Question 31?? y A?

1- incorrect, activation energy is 90, enthalpy change is +30,
2- correct, since reactants have greater energy than products.
3- correct, since -30 to reach products, as is exothermic.

 

[ZaqZainab]

1- incorrect, activation energy is 90, enthalpy change is +30,
2- correct, since reactants have greater energy than products.
3- correct, since -30 to reach products, as is exothermic.

you checked the wrong paper
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s13_qp_12.pdf here is the paper though i explained it already

 

[..sacrifice4Revenge..]

you checked the wrong paper
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s13_qp_12.pdf here is the paper though i explained it already

m going.

first i did q33 thinking it ws 31, then started 31 thought its 30 and so deleted. now did 32 instead of 31.
good night. >.<

 

[ZaqZainab]

m going.

first i did q33 thinking it ws 31, then started 31 thought its 30 and so deleted. now did 32 instead of 31.
good night. >.<

Lol yeah you can go

 

[dumb human]

1- incorrect, activation energy is 90, enthalpy change is +30,
2- correct, since reactants have greater energy than products.
3- correct, since -30 to reach products, as is exothermic.

i thought all are correct :/

 

[kingo44]

3 In aqueous solution, the acid HIO disproportionates according to the following equation where m,
n, p and q are simple whole numbers in their lowest ratios.

mHIO → nI2 + pHIO3 + qH2O

This equation can be balanced using oxidation numbers.

What are the values for n and p?

n p
A 1 2
B 2 1
C 4 1
D 4 2

 

[kingo44]

please hwowowwwwwwwwwwwwwwwwwwwwwwww

 

[unique111]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_12.pdf
Q.4 C
Q.6 B (why not C?)
Q.10 A
Q.11 C ( why not A? Doesn't Br go from -1 to 0?)
Q.17 c
Q.18 D ( but question says made from water?
Q.26 A
Q. 29 D
Q. 35 B
Q.37 D
Q. 40 A
Please, somebody clear these doubts?

 

[unique111]

3 In aqueous solution, the acid HIO disproportionates according to the following equation where m,
n, p and q are simple whole numbers in their lowest ratios.

mHIO → nI2 + pHIO3 + qH2O

This equation can be balanced using oxidation numbers.

What are the values for n and p?

n p
A 1 2
B 2 1
C 4 1
D 4 2

Here's the link to the solution. But i don't get it. Hope you do. Plz, explain to me too.
https://www.xtremepapers.com/commun...-for-chemistry-only.19324/page-23#post-609519