Chemistry: Post your doubts here!

[chocolate_girl]

Sorry for the crappy drawings. In my defence, drawing has never been my strength

Thankyou soo much

 

[Faaiz Haque]

For the reaction of tollens reagent with an aldehyde the aldehyde gets converted into a carboxylic group. For the second one what you do is you remove the H2 from the 2,4 dinitrophenylhydrazine and from the other compound remove the O that is doubly bonded to the C. And then join both molecules together. The writing after the arrow is what should be written in the answer, the diagram before the arrow is for explanation.
View attachment 40925

thanks man

 

[thats_me]

Thanks a lot, I got it now
If you don't mind, could you please help me with qn no. 3(c) of this paper? It's a similar one.. and I'm completely confused
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_42.pdf

Ekh I'm stuck with this too :/

 

[_Ahmad]

Can anyone please help me with this question
calculate average bond energy of C-C bond in ethane given ΔHf(C2H6) = -85 KJ/mol , ΔHat(H)gas =218 KJ/mol and ΔHat(graphite) = 715 KJ/mol

 

[Browny]

Can I have M/J 2001 chemistry 02?

 

[Browny]

Thanx Dude! is this revision giude?

Can you give me the chemistry papers theory from 2000 to 2002 please?

 

[Mohammed salik]

Can you give me the chemistry papers theory from 2000 to 2002 please?

I actually started from O/n 2002!!
Sorry

 

[GCE As and a level]

hey guys
how are u all?
i need a help in http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s12_qp_23.pdf Q3 c) , Q4 c) and f) ,Q5 c) and d)
waiting your help
thanks in advance

 

[Logitech]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w07_qp_32.pdf
In this paper in Q1b how should I know which experiment to follow?

does anyone know how to do this?

 

[abruzzi]

Ekh I'm stuck with this too :/

Please let me know if you find the solution to it

 

[salvatore]

w.r.t. H2O2 :
0.70/.05 = 1.4/1.0
7/5 = 7/5

w.r.t. H+ :
if we consider the conc of H2O2 first and compare it with rate:
0.09/0.05 = 1.8/1.0
9/5 = 9/5

it shows that the rate is changing just because of H2O2 .... which means that however much the conc of H+ changes, it won't have any effect on the rate of reaction. so wrt H+ the order of reaction is 0

Thanks a lot man, peace!

 

[daredevil]

Thanks a lot man, peace!

np!! (Y)

 

[daredevil]

Ekh I'm stuck with this too :/

it's a matter of the discharge priority stuff in electrlysis...
u know the reactivity series of metals that we did in O levels too?

so according to that, O2 is discharged in preference to SO4-2 and F- so it is discharged before F2 or SO2...
Br2 however is discharged in preference to O2.

similarly work with the reactivity series for metals... which will account for the discharge at the cathode.

 

[robinhoodmustafa]

hey guys
how are u all?
i need a help in http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s12_qp_23.pdf Q3 c) , Q4 c) and f) ,Q5 c) and d)
waiting your help
thanks in advance

did my best to explain. dont mind my writing. i was writing in on 'paints'
Q3 c

4c

4f

5c

 

[Browny]

does anyone know how to do this?

Yes,just calculate.

 

[GCE As and a level]

did my best to explain. dont mind my writing. i was writing in on 'paints'
Q3 c

4c

4f

5c

really thank you for your help dont worry about the hand writing
can u plz also explain to me Q3 d) and Q 5 d)
and can u explain in more depth Q 5 C) the last step

i really appreciate your help

Wish u good luck

 

[robinhoodmustafa]

really thank you for your help dont worry about the hand writing
can u plz also explain to me Q3 d) and Q 5 d)
and can u explain in more depth Q 5 C) the last step

i really appreciate your help

Wish u good luck

Mole ratio is 1:1
so each mole of C3H6O3 will give 1 mole of H2
so you have mass of C3H6O3 so calculate moles and multiply it by 24000 so calculate volume of gas
See, 1 Moles occupy 24 dm3 (24000 Cm3) so you can even apply the cross wala method.
1 --- --------24000
6.67*10^3 -----x

x= 160 cm3



alcohols have hydrogen bonding between O and H so that it why they are polar and Hydrogen bond is stronger to hold the liquid particle while the DME gas compound has weak vander waals


and sorry i m weak in ester isomer. need to work on it

pls do pray for me.

 

[GCE As and a level]

hey guys
how are u all?
i need a help in(unsolved questions) and can u check the solved questions to me?

waiting your help
thanks in advance

 

[GCE As and a level]

Mole ratio is 1:1
so each mole of C3H6O3 will give 1 mole of H2
so you have mass of C3H6O3 so calculate moles and multiply it by 24000 so calculate volume of gas
See, 1 Moles occupy 24 dm3 (24000 Cm3) so you can even apply the cross wala method.
1 --- --------24000
6.67*10^3 -----x

x= 160 cm3



alcohols have hydrogen bonding between O and H so that it why they are polar and Hydrogen bond is stronger to hold the liquid particle while the DME gas compound has weak vander waals


and sorry i m weak in ester isomer. need to work on it

pls do pray for me.

Thank you,
Can u plz also check my other doubt ???
Wish u good luck

 

[GCE As and a level]

Mole ratio is 1:1
so each mole of C3H6O3 will give 1 mole of H2
so you have mass of C3H6O3 so calculate moles and multiply it by 24000 so calculate volume of gas
See, 1 Moles occupy 24 dm3 (24000 Cm3) so you can even apply the cross wala method.
1 --- --------24000
6.67*10^3 -----x

x= 160 cm3



alcohols have hydrogen bonding between O and H so that it why they are polar and Hydrogen bond is stronger to hold the liquid particle while the DME gas compound has weak vander waals


and sorry i m weak in ester isomer. need to work on it

pls do pray for me.

inshallah u will get the highest grade in all your subjects