Chemistry: Post your doubts here!

[Jinkglex]

Ty daredevil, btw im appearing from Lahore too

And Ahmedraza, half equations show participants of the reaction removing spectator ions:

e.g: CUS04 + ZN -> ZNSO4 + Cu.

as SO4 anion remains constant and doesnt change in oxidation state it simply becomes

Cu2+ + Zn-> Zn2+ + Cu.

I didnt show charges on the former equation but im sure you know their individual oxidation states

 

[daredevil]

Can anyone me the Colour list of compounds?
Please anyone can anyone post it

how do u mean colour list??
ummm generally metal compounds are all white except for transition metals
Iodide and also chromate compounds with transition metals are yellow

if i am wrong plz correct me ppl =)
and thanku for the reference Jinkglex =) i'll take that as a compliment ^_^

 

[knowitall10]

Aoa wr wb

Can someone please draw a diagram for qn 1 of this paper ?

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s12_qp_52.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s12_ms_52.pdf

Thanx a lot


PS: I'd really appreciate if someone can upload solved paper 5s for chemistry qn 1 of different years, thanx

Here's the diagram:
I didn't check the mark scheme though....
I'll do it now..

 

[ZainH]

Electrophilic substitution occurs only in Benzene and Aryl compounds as far as i know, which only appear in A2.

And sure Alice np, just lemme finish my read-through of the book and i'll share 'em

Are you sure it's not included..? e_e

 

[Jinkglex]

AFAIK, Partition coefficient is A2 material [Chromatography, ugh!] And thus will not be coming in tomorrows paper. Besides that, I'd rather have refreshed it in my mind before relating it to you, but in summary, it is the degree to which something gives preference to one solvent over another. The greater its partition coeffecient in a particular medium, the greater its likelihood to dissolve within it and either move forward if the solvent happens to be the mobile phase, or stick in the a static position if the solvent was the stationary phase. It measures the CONCENTRATION of the SOLUTE in each solvent and forms an equation relating the two in a RATIO method. Kind of like Asking a group of people if they prefer PMLN or PTI and making a survey out of it

 

[knowitall10]

Are you sure it's not included..? e_e

nope.. not included in AS

 

[ZainH]

AFAIK, Partition coefficient is A2 material [Chromatography, ugh!] And thus will not be coming in tomorrows paper. Besides that, I'd rather have refreshed it in my mind before relating it to you, but in summary, it is the degree to which something gives preference to one solvent over another. The greater its partition coeffecient in a particular medium, the greater its likelihood to dissolve within it and either move forward if the solvent happens to be the mobile phase, or stick in the a static position if the solvent was the stationary phase. It measures the CONCENTRATION of the SOLUTE in each solvent and forms an equation relating the two in a RATIO method. Kind of like Asking a group of people if they prefer PMLN or PTI and making a survey out of it

nope.. not included in AS

Oh wait, you guys are right lol..
I for some reason was thinking about electrophilic addition.. there's no substitution, it's free radical-substitution.
Riiiiiiight.

 

[knowitall10]

which is better to condense water vapour: a Liebig condenser or a U tube in a beaker of ice?

 

[knowitall10]

and to collect gas, which one is better: collecting it in an inverted gas jar (under water) or a graduated gas syringe?

 

[MaxStudentALevel]

AFAIK, Partition coefficient is A2 material [Chromatography, ugh!] And thus will not be coming in tomorrows paper. Besides that, I'd rather have refreshed it in my mind before relating it to you, but in summary, it is the degree to which something gives preference to one solvent over another. The greater its partition coeffecient in a particular medium, the greater its likelihood to dissolve within it and either move forward if the solvent happens to be the mobile phase, or stick in the a static position if the solvent was the stationary phase. It measures the CONCENTRATION of the SOLUTE in each solvent and forms an equation relating the two in a RATIO method. Kind of like Asking a group of people if they prefer PMLN or PTI and making a survey out of it

That's actually exactly what I needed, thanks! You're going to do great in the exams IA your concepts are in such awesome order

 

[Enferno]

and to collect gas, which one is better: collecting it in an inverted gas jar (under water) or a graduated gas syringe?

Depends on gas

 

[MaxStudentALevel]

and to collect gas, which one is better: collecting it in an inverted gas jar (under water) or a graduated gas syringe?

Usually under water but it will say specifically "REDUCE/MINIMIZE GAS LOSSES" and that's your hint for over water!

 

[Jinkglex]

Theres also nuecleophilic substitution.

And Alice:

All period 3 elements react with Oxygen [except argon, ofcourse]

They form oxides and burn with varying flame colors [White for MG/AL, blue for sulphur, yellow for phosphorous etc] The oxide formula depends on their valency and some exist as different oxides [e.g SO2, SO3].

They form chlorides [except Chlorine, ofcourse, and argon] as well, but these usually have a constant formulae.

They will ALWAYS BE POSITIVE OXIDATION NUMBER as they react with elements MORE ELECTRONEGATIVE THEN THEMSELF.

For example Na gives Na+ usually, makes Na2O
Mg gives Mg2+, gives MgO

Couldnt really find anything besides these....unless you meant reactions with water which are more towards RATTA then conceptual learning

 

[Enferno]

Usually under water but it will say specifically "REDUCE/MINIMIZE GAS LOSSES" and that's your hint for over water!

If the gas is water soluble? like I said, depends on gas

 

[Jinkglex]

Oh yeah and besides that, they get lower in reactivity going across the group with Cl.

 

[MaxStudentALevel]

If the gas is water soluble? like I said, depends on gas

Oh they'll mention that. It'll literally hint at what apparatus is appropriate in the question.

 

[Enferno]

Oh they'll mention that. It'll literally hint at what apparatus is appropriate in the question.

yeah, exactly

 

[knowitall10]

Just a side question: does almost everyone know urdu here??

 

[Enferno]

Just a side question: does almost everyone know urdu here??

I do

 

[PANDA-]

Question guys..

C4H8O2 contains C=C and OH ... Two types of steroisomerism exist for this compound... Draw the displayed formula of both pairs of isomers ( 4 compounds )

One is cis-trans...
This is the marking scheme's answer

This is my answer: ( i was too lazy to draw the trans in paint... )

Now my question, is the marking scheme answer the only answer they accept, because that would be just unfair