Chemistry Doubts: IGCSE Paper 3

[zaid1q]

guys guys where can i find chemistry from 1990??!?! plz plz

 

[Manobilly]

but i dont get it u gave the example of silicon and flourine but its bromine...or do u just mean to say that u can use any halogen to solve it

the question and varient the person told me had fluorine.

 

[RoyalPurple]

RoyalPurple
thanks alot <3

 

[Manobilly]

Oh okey,Good luck

 

[RoyalPurple]

guys guys where can i find chemistry from 1990??!?! plz plz

check www.freeexampapers.com

im nt sure though

 

[zaid1q]

i

check www.freeexampapers.com

im nt sure though

its nt woking :/

 

[RoyalPurple]

i
its nt woking :/

 

[Beedo]

Pleeeaaase , J04 no 4-(a)ii -4-(b)
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s04_qp_3.pdf
I really need help for those

 

[ZainH]

Got a small question, I realize paper 3 includes EVERYTHING, but do we have to know the tests and what not.. or were those for only p6?

 

[Abu mota]

Pleeeaaase , J04 no 4-(a)ii -4-(b)
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s04_qp_3.pdf
I really need help for those

4 a)ii) this is precipitation any soluble zinc salt like for example: zinc nitrate+sodium carbonate= zinc carbonate+ sodium nitrate.
4 b) Fe+ 3OH= Fe(OH)3 doesnt need explanation
ii) i dont know why srry

 

[Mozmozil]

Pleeeaaase , J04 no 4-(a)ii -4-(b)
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s04_qp_3.pdf
I really need help for those

2NaCl + Pb(NO3) 2-----> 2Na(NO3) + PbCl2
for this you need to knw the reactivity series of metals
Please ( potassium)
Stop (Sodium)
Calling (Calcium)
My (Magnesium)
African (Aluminum)
Cool (Carbon)
Zebra (Zinc)
In (Iron)
Latin, (Lead)
History (Hydrogen)
Class (Copper)
She (Silver)
Grunts (Gold)
People (Platinum)
(double displacement will occur)So since Na is more reactive than lead so it will displace it .
And in precipitation methode,, soluble salt+soluble salt= insoulabe salt(PbCl2) + soluble 2Na(NO3) . P.S I hope this is correct lol

 

[Emmanuel T.]

can someone plz quickly describe in outline the processes of extracting iron and steel!plz plz...just quick summary of important points!

 

[thats_me]

2NaCl + Pb(NO3)2-----> 2Na(NO3) + PbCl2
for this you need to knw the reactivity series of metals
Please ( potassium)
Stop (Sodium)
Calling (Calcium)
My (Magnesium)
African (Aluminum)
Cool (Carbon)
Zebra (Zinc)
In (Iron)
Latin, (Lead)
History (Hydrogen)
Class (Copper)
She (Silver)
Grunts (Gold)
People (Platinum)
(double displacement will occur)So since Na is more reactive than lead so it will displace it .
And in precipitation methode,, soluble salt+soluble salt= insoulabe salt(PbCl2) + soluble 2Na(NO3) . P.S I hope this is correct lol

lol hahaha i thought i was the only one
please
stop
calling
my
aunt
carol
zine
inanimate
things
like
honey
comb
sugar
gooey
plop

 

[Mozmozil]

lol yeah its a gd way to remember stuff,,specially for chemii ;P

 

[Abu mota]

can someone plz quickly describe in outline the processes of extracting iron and steel!plz plz...just quick summary of important points!

Hi,
i will make it in bulllet points:
- first u need to add limestone and hematite and coke
- the coke burns and provides heat for the reaction and releases CO2
- the CO2 reacts with more carbon to get carbon monoxide
- carbon monoxide reduces the iron oxide to pig iron
-limestone decomposes to CaO which neutralises the acidic impurities especially silicon oxide
- This forms slag this is less dense than iron and so it floats on top of it preventing iron from oxidation.

To make steel from pig iron:
first add oxygen to oxide carbon to carbon dioxide and monoxide which escape and also it oxide silicon to silicon oxide and then u add CaO which neutralizes the silcon oxide and then the steel can be extracted.
* make sure that u dont remove all of the carbon as this will cause the iron to oxidise back to iron oxide.

 

[Emmanuel T.]

Hi,
i will make it in bulllet points:
- first u need to add limestone and hematite and coke
- the coke burns and provides heat for the reaction and releases CO2
- the CO2 reacts with more carbon to get carbon monoxide
- carbon monoxide reduces the iron oxide to pig iron
-limestone decomposes to CaO which neutralises the acidic impurities especially silicon oxide
- This forms slag this is less dense than iron and so it floats on top of it preventing iron from oxidation.

To make steel from pig iron:
first add oxygen to oxide carbon to carbon dioxide and monoxide which escape and also it oxide silicon to silicon oxide and then u add CaO which neutralizes the silcon oxide and then the steel can be extracted.
* make sure that u dont remove all of the carbon as this will cause the iron to oxidise back to iron oxide.

thnx bro...YOU ARE A HERO!

 

[Abu mota]

lol hahaha i thought i was the only one
please
stop
calling
my
aunt
carol
zine
inanimate
things
like
honey
comb
sugar
gooey
plop

Kittens (potassium
Not (sodium)
Little (lithium)
Cats (calcium)
Make (magnesium)
A (aluminum)
Cheap (carbon)
Zoo (zinc)
For ( iron)
Poor ( lead)
Hungry (hydrogen)
Children ( copper)

 

[owais rafiq]

explain mentioning both rate and yield why contact process temp is 450 degree celsius?? plzz sumbodyy helpp here!!

 

[Abu mota]

explain mentioning both rate and yield why contact process temp is 450 degree celsius?? plzz sumbodyy helpp here!!

hi,
450 degree Celsius is used because it is a compromise i.e it makes sure that the rate stays as fast as possible without causing the equilibrium position to move to the endothermic direction which is the backward reaction causing a decrease in the yield.
I hope i helped, if u need anything just post here

 

[Emmanuel T.]

explain mentioning both rate and yield why contact process temp is 450 degree celsius?? plzz sumbodyy helpp here!!

450 degrees is low enough to give a high yield, and is high enough to give a faster rate of reaction! >>>HOPE IT HELPED!