Chemistey Doubts

[xIshtar]

hey i got a doubt!!!


thnx!!

The answer is:

hey i got a doubt!!!


thnx!!

i think it's D..
coz potassium is high in reactivity.
and it is soluble.
barium sulphate is insoluble. so it can't dissolve in water.

And basically, because it is ionic, and the only soluble ionic there

 

[JmCullen]

ok!
let's concentrate on paper 3 now.

how to find the average reaction rate?
Q3b
http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

 

[MohammedNoor]

viewtopic.php?f=24&t=9553


everyone plz help me to clear my doubts.........in the new topic

 

[JmCullen]

ok!
let's concentrate on paper 3 now.

how to find the average reaction rate?
Q3b
http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

can anyone do this?

 

[shan5674]

ok!
let's concentrate on paper 3 now.

how to find the average reaction rate?
Q3b
http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

can anyone do this?

I dont get that either

 

[JmCullen]

how to find the average reaction rate?
Q3b
http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf[/quote]


Q4b. Can it be cracking of alkane? what i know cracking of alkane produce alkene and hydrogen right?
http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

 

[HorsePower]

i forgot how to do the first one ............
but for the second one , you have to write catalytic cracking and then also mention that the alkane needs to be heated at a very high temperature .

 

[gary221]

ok!
let's concentrate on paper 3 now.

how to find the average reaction rate?
Q3b
http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

can anyone do this?

actually this is quite tricky!!

u hve to divide the vol.by the time to get the rate
so to get d 1st rate,vol = 48cm3 time = 20 s so rate = vol/time = 48/20 = 2.4
d 2nd one vol = 70-48 =22 time = 20 s =22/20 = 1.1
hope u got it!!

 

[Suha123]

Hey guys!

Could anyone help me out with question 5(c)(ii),please? It completely went over my head :unknown:

Please reply asap! So nervous atm Much appreciated!
http://www.xtremepapers.me/CIE/Cambridg ... 3_qp_3.pdf

 

[LimeReem]

Hey guys!

Could anyone help me out with question 5(c)(ii),please? It completely went over my head :unknown:

Please reply asap! So nervous atm Much appreciated!
http://www.xtremepapers.me/CIE/Cambridg ... 3_qp_3.pdf

You know a base as a proton (H) acceptor , so NH3 + H --> NH4

 

[Suha123]

I'm sorry but there's no NH3 in the question :/

 

[CaptainDanger]

SO2 is oxidised by Bromine to sulphate... It reacts with Barium to form the white ppt of barium sulphate...

 

[JmCullen]

Q4(b)(i)
http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

why colour change from colourless to brown?
why brown?
because of iodine?

 

[xIshtar]

Q4(b)(i)
http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

why colour change from colourless to brown?
why brown?
because of iodine?

No.. Potassium iodide is a reductant in acidic conditions. So, the colour changes from colourless to brown in the presence of an oxidant..

 

[xIshtar]

But in short, the colour change is partially down to the iodine.

 

[CaptainDanger]

Q4(b)(i)
http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

why colour change from colourless to brown?
why brown?
because of iodine?

Yes... Its a test for oxidising agent... If any oxidising agent is present in the solution (Ozone here) The iodide ions will be changed to iodine... From colouless to brown...

 

[JmCullen]

Thanks a lot people!!!!
appreciate it!


another question here..
about the drawing part. ugh.. im always bad in drawing.

http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

Q5(b)

 

[CaptainDanger]

 

[xIshtar]

Thanks a lot people!!!!
appreciate it!


another question here..
about the drawing part. ugh.. im always bad in drawing.

http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

Q5(b)

Make it tetrahedral, and make sure that you maintain the ratio as in Silicon(iv) oxide.
Which is, 1 Silicon : 4 Oxygen
2 Oxygen : 1 Silicon

Thus the formula is maintained.

 

[JmCullen]

Thanks a lot people!!!!
appreciate it!


another question here..
about the drawing part. ugh.. im always bad in drawing.

http://www.xtremepapers.me/CIE/Cambridg ... _qp_32.pdf

Q5(b)

Make it tetrahedral, and make sure that you maintain the ratio as in Silicon(iv) oxide.
Which is, 1 Silicon : 4 Oxygen
2 Oxygen : 1 Silicon

Thus the formula is maintained.

O
l
Ge
/ l \
O O O
/ \ / \ / \
Ge Ge Ge Ge Ge Ge

is it something like this??