Chemistry: Post your doubts here!

[geek101]

the kazillionth time im posting this http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_12.pdf Q4

 

[angelicsuccubus]

the kazillionth time im posting this http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_12.pdf Q4

I'll check it out, hang on..
Can anyone do this? q11
How do you do q11 in http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s11_qp_12.pdf

 

[Goku]

in the orignal molecule there are 9 double bonds if you count them......................in the residue one chain hai 2 double bonds and 2chains have 1 double bond thus total is 4.....so the bonds that are saturated are 9-4=5


I HOPE YOU GET IT NOW

Yes I do!!
Thankyou so much!
but dont caps lock dude,sorry im a big explanation need-er

 

[Casablanca]

How many isomers with the structure C5H10 have structures involving pi bonds?

A. 3
B. 4
C. 5
D. 6

Why?

 

[Goku]

How many isomers with the structure C5H10 have structures involving pi bonds?

A. 3
B. 4
C. 5
D. 6

Why?

Ermm,they must all be alkenes yeah? cos Pi bonds are only found in double bonds ..

 

[cHeStEr]

NEED SERIOUS HELP !!!!!​

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_11.pdf 6,9

http://www.xtremepapers.com/CIE/International A And AS Level/9701 - Chemistry/9701_s07_qp_1.pdf 9

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s06_qp_1.pdf 10,15

thnxzz in advnce agn...

 

[angelicsuccubus]

the kazillionth time im posting this http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_12.pdf Q4

ack I donno! I got 1360Kg -_-

 

[Muhammad Asif]

the kazillionth time im posting this http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_12.pdf Q4

the equation is N2+3H2----->2NH3

in the start moles of H2=60......... at equlibrium H2 moles=48....thus change in moles=60-48=12

from the equation the ratio of H2:NH3=3:2...............thus moles of NH3 produced would be (2*12)/3=8moles.....
Mass=Mr*moles
Mass=(14+3)*8
Mass=17*8
Mass=136Kg

 

[angelicsuccubus]

Ermm,they must all be alkenes yeah? cos Pi bonds are only found in double bonds ..

yep

 

[hihi]

can someone help me with question 39:
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w08_qp_1.pdf

 

[angelicsuccubus]

the equation is N2+3H2----->2NH3

in the start moles of H2=60......... at equlibrium H2 moles=48....thus change in moles=60-48=12

from the equation the ratio of H2:NH3=3:2...............thus moles of NH3 produced would be (2*12)/3=8moles.....
Mass=Mr*moles
Mass=(14+3)*8
Mass=17*8
Mass=136Kg

wait wait1 how'd you get the moles of H2 as 60 and 48?

 

[Student12]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w10_qp_12.pdf

Q 7 , 8, 12, 14, 22,
28 why isnt it A or C ?

Explain please !

 

[Pals_1010]

Hello how do you look for a chiral carbon atom in a cyclic or aromatic compound please? Thx

 

[Muhammad Asif]

wait wait1 how'd you get the moles of H2 as 60 and 48?

because Mr of H2=(2*1)=2
moles=mass/mr
moles=120/2
moles=60
same for moles at equilibrium

 

[Muhammad Asif]

Hello how do you look for a chiral carbon atom in a cyclic or aromatic compound please? Thx

in such molecules mostly a chiral centre is found is where 3 line join if any chain isnt the same as other 3

 

[hihi]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf

Q 7 , 8, 12, 14, 22,
28 why isnt it A or C ?

Explain please !

for 28: u do not write H in skeletal formula
for 14 try working out with M(Ca(NO3)2 )

 

[nazzzzzz]

What's that reaction involved with KMnO4 and alchohols? I can't seem to understand. Please help me I need an answer desperately

 

[angelicsuccubus]

because Mr of H2=(2*1)=2
moles=mass/mr
moles=120/2
moles=60
same for moles at equilibrium

aack thanks.. sorry I haven't done chem in so long.. I was taking the 3 in 3H2 in account too

 

[Casablanca]

What's that reaction involved with KMnO4 and alchohols? I can't seem to understand. Please help me I need an answer desperately

Oxidation.

 

[Goku]

Ermm anybody got tips for MCQ exams?
All the choices look so alike,and the calculations are </3 :'(