Chemistey Doubts

[gary221]

actually thts becoz the no. of moles for oxygen=0.067
and in the equation its like 1 molecule of oxygen on 1 side and 2 molecules of lead nitrate on the other side
so 0.067*2 = 0.013

 

[JmCullen]

actually thts becoz the no. of moles for oxygen=0.067
and in the equation its like 1 molecule of oxygen on 1 side and 2 molecules of lead nitrate on the other side
so 0.067*2 = 0.013

oh!!! right! omg!
what happen to me. hahahaha..
sort of headache. phew~

 

[JmCullen]

Re: chemistry

i have some problem in the following question i will really appriciate if u ppl help me in this!!
http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf
question number 8(c) in this link.


this is the mark scheme:
http://www.xtremepapers.me/CIE/Cambridg ... _ms_32.pdf

mole of oxygen = 0.16dm3 (divide) 24dm3 = 1/150 mol
mole of lead(II) nitrate = 1/150 (times) 2 = 0.0133 mol
mass of lead(II) nitrate = 0.0133 (times) 331 = 4.41g
percentage = 4.41 (divide) 5 (times) 100% = 88.3%

With the help of gary221 too!!!!

 

[JmCullen]

oh! btw, what is the structure of nylon? perhaps can you draw it out? Thanks a lot!

 

[haochen]

oh! btw, what is the structure of nylon? perhaps can you draw it out? Thanks a lot!

hope it helped

 

[CaptainDanger]

oh! btw, what is the structure of nylon? perhaps can you draw it out? Thanks a lot!

 

[haochen]

 

[CaptainDanger]

 

[gary221]

cud sum1 pls help me with this????

P.S. with an explnation!!! :friends: :friends: :friends:

 

[saraiqbal123]

me too em stuck in the second part!!

 

[gary221]

oh! btw, what is the structure of nylon? perhaps can you draw it out? Thanks a lot!

hey its d same structure which i drew earlier!!!

 

[gary221]

me too em stuck in the second part!!

r u talkin bout the previous ques?????


i hve no idea at all!!!!

 

[Ahsen420]

Chemistry P3 Doubts, Please Help

I have some doubts related 2 Chem P3 Papers.

SORRY I COUDN'T POST THE LINK COZ' I'M WORKIN ON MOBILE (MY LAPTOP'S BROKENS), I CAN'T COPY/PASTE. THE subject CODE is 620 and paper code 03

P03, ON 2007
4(b)
5(a)(i)
6(b)
6(c)(iii)
6(d)(i)-(iii)
7(b)(i)(ii) what is reagent in excess and reason
7(b)(iii)

 

[SpiritualGlory]

Chemistry Paper 3 doubt!
MAY/JUNE 2009 Q)5 b) part
http://www.xtremepapers.me/CIE/Cambridg ... 9_qp_3.pdf
how to we get the formula for T? And what is the explanation!

 

[haochen]

Chemistry Paper 3 doubt!
MAY/JUNE 2009 Q)5 b) part
http://www.xtremepapers.me/CIE/Cambridg ... 9_qp_3.pdf
how to we get the formula for T? And what is the explanation!

i figured out the answer but it is sooo hard and i think ill try my best to explain it to u
first we write down the equation
the we solve for the mole (something related to math)
then we find the ratio of the mole of the reactant and product
then we substitute them in the equation.
after that balance the equation by putting number for the element (dont change the mole number)

hope u got it

 

[haochen]

Re: Chemistry P3 Doubts, Please Help

I have some doubts related 2 Chem P3 Papers.

SORRY I COUDN'T POST THE LINK COZ' I'M WORKIN ON MOBILE (MY LAPTOP'S BROKENS), I CAN'T COPY/PASTE. THE subject CODE is 620 and paper code 03

P03, ON 2007
4(b)
5(a)(i)
6(b)
6(c)(iii)
6(d)(i)-(iii)
7(b)(i)(ii) what is reagent in excess and reason
7(b)(iii)

which month???

 

[JmCullen]

cud sum1 pls help me with this????

P.S. with an explnation!!! :friends: :friends: :friends:

It's A..
unsaturated should be double bond..
Then, C is acid.
acid can't be neutral in water.
so it's A..

 

[JmCullen]

Re: Chemistry P3 Doubts, Please Help

I have some doubts related 2 Chem P3 Papers.

SORRY I COUDN'T POST THE LINK COZ' I'M WORKIN ON MOBILE (MY LAPTOP'S BROKENS), I CAN'T COPY/PASTE. THE subject CODE is 620 and paper code 03

P03, ON 2007
4(b)
5(a)(i)
6(b)
6(c)(iii)
6(d)(i)-(iii)
7(b)(i)(ii) what is reagent in excess and reason
7(b)(iii)

4(b)(i) boiling and condensation. (distillation should be boil first then it will condense to form whatever they are looking for)
(ii) to get maximum yield of zinc. when carbon increase forward reaction is favour.

5(a)(i) backward reaction is favour.

6(b) propan-2-ol is okay~~ just draw the OH at the second carbon.

6(c)(iii) high pressure. volume is decrease, hence forward reaction is favour.

6(d)(i) methyl ethanoate (methanol and ethanoic acid)
(ii) propanoic acid (when acid is oxidise, or react with oxygen, acid will form)
(iii) ethene (ethene react with steam forms ethanol)

7(b)(i) CaCO3, because the ration is 1:2. so they only need (0.003/2) = 0.0025 of CaCO3. but they have 0.003. so CaCO3 is excess.
(iii) 24 (times) 0.0025 = 0.06dm3


hope you understand what im trying to explain. haha

 

[JmCullen]

can anyone draw this structure for me please..

http://www.xtremepapers.me/CIE/index.ph ... 3_qp_3.pdf

3(d)(ii)

thanks in advance.

 

[haochen]

can anyone draw this structure for me please..

http://www.xtremepapers.me/CIE/index.ph ... 3_qp_3.pdf

3(d)(ii)

thanks in advance.

he name is propene (count the number of carbon and see the number of hydrogen)
drawing : attachment

hope u got it