Chemistry: Post your doubts here!

[Goku]

1 chain has 2 double bond in residue and two chains contain single double bond in them thus the number of double bond saturated=5(9-4)
1 double bond require 1 mole of H2 so 5mol are require

Thankyou but I dont get it :'(
how did you get 9-4? :/

 

[Muhammad Asif]

Which formulae show propanone and propanal as different compounds?

A. Emperical, molecular, structural and displayed formulae.
B. Molecular, structural and displayed formulae.
C. Structural and displayed formulae only.
D. Displayed formulae only.

I think it's C. Can someone confirm this, please?

yes it is as only structured and display formula will show you the position of the bond

 

[Casablanca]

The answer is D, this is because in enthalpy change of formation, or any enthalpy change...the reactants must be in their standard states, carbon exists as solid, while H2 is a gas. So the answer is either C or D. in the enthalpy changes the products formed are in gaseous state, so the answer is C. you mind telling the year so i can confirm the answer!

May/June 2011 Paper 9701/12, question 8. So... is it C or D?

 

[geek101]

May/June 2011 Paper 9701/12, question 8. So... is it C or D?

its C

 

[Muhammad Asif]

Thankyou but I dont get it :'(
how did you get 9-4? :/

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

 

[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