Chemistry: Post your doubts here!

[syed1995]

check ur 2nd equations there are too many Cl in the reactants

ah yeah.. it's 5NaCl..

 

[daredevil]

RCOOH + XCO3 ---> CO2 + H2O + salt
e.g. 2CH3COOH + CaCO3 ---> (CH3COO)2Ca+ H2O + CO2

I got it off google
I don't think you need to know the equation. In the papers I answered some papers, according to that what I know is that you need to know that CO2 is given out (effervesence) and this CO2 turns limewater milky.

thanksss man!! thats the right one,.... yeah but according to syllabus i think we do need to know.... and seeing the imbeciles the cie people are u never know wat hey might give in the paper -__-

 

[daredevil]

ah yeah.. it's 5NaCl..

yuppo

 

[syed1995]

What are the tests for identifying gases?

like for SO2?

 

[Manobilly]

plz I need solution for solving Kc ! In mj 2007.need an idea abt solving questions like that.

 

[daredevil]

thanks MustafaMotani i just wanted to confirm these conditions were ued because at one place i have written them and in the other i haven't so last min confusion atack ho raha tha

 

[daredevil]

What are the tests for identifying gases?

like for SO2?

its by using a filter paper soaked in acidified K2Cr2O7 i think.... it turns orange to green.... the one we did in o levels

 

[MustafaMotani]

What are the tests for identifying gases?

like for SO2?

SO2 turn dichromate from orange to green .. in other words it gets oxidised ..

daredevil i understand..

 

[PANDA-]

Guys discuss AS here:
https://www.xtremepapers.com/commun...-p1-and-p2-doubts-only-only-as-allowed.25455/

 

[strangerss]

hey every one , all salam alaykum. I have a question what would be produced if a carbon in an alkene involved in the double bon was also bonded to a hydrogen AND a bromine or any halogen and then it was treated with cold dilute manganate ion AND hot concentrated manganate ions ?? Would such a thing be tested in exams 0.o?

 

[strangerss]

Whats the difference between writing 3+ and +3 in oxidation numbers??please help

 

[A star]

Whats the difference between writing 3+ and +3 in oxidation numbers??please help

nothing i guess

 

[daredevil]

Whats the difference between writing 3+ and +3 in oxidation numbers??please help

plz come to that other thread that is for the AS questions only...
and i don't think there is any such difference its just a standard for writing it and that is 3+

 

[knowitall10]

Thanx a bunch for this man!
JazakAllah khair

PS: That's pretty neat ^_^

PPS: Oh and you've placed the ammonium ntrate just like that on the tube, i think it needs a porcelain dish

Wa iyyaki sis
Does it say that in the mark scheme? How am i supposed to draw the procelain dish? (excuse my spelling there plz)
Can u upload ur diagram pls? I'd like to see it...

 

[Soldier313]

Wa iyyaki sis
Does it say that in the mark scheme? How am i supposed to draw the procelain dish? (excuse my spelling there plz)
Can u upload ur diagram pls? I'd like to see it...

I believe it's this (just chipped it in, into your drawing )

 

[knowitall10]

I believe it's this (just chipped it in, into your drawing )


View attachment 25142

Ohh... thanks dude... i didnt know that... i'll make a note of that point..
JAzki Allahu Khair

 

[zain786]

Q3(b)
PLZ
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_qp_52.pdf

 

[strangerss]

I

nothing i guess

In oct/nov 2002 they say in the marking scheme along with +3 NOT 3+ :S , QUESTION 3D

 

[Trash Can]

plzz anyone give me a list of apparatus with their volumes and usage...plzzz help me..:'( im seriously stuck with p5...especially the first question of planning and designing experiments...plzz help.. :'(

 

[syed1995]

I

In oct/nov 2002 they say in the marking scheme along with +3 NOT 3+ :S , QUESTION 3D

There is a difference between valency and oxidation number.. Oxidation number is always in the +3 or -3 format.. while valency can either be 3+ or +3 .. doesn't matter.