Chemistry: Post your doubts here!

[RGBM211]

Is reflux necessary? Well could not remember it clearly.
As long as the materials are mixed and conditions applied, the reaction occurs, yet taking equal amounts can ensure no remaining reactants afterwards I would say.

kinda its given in markscheme yep without reflux the reaction cnt be carried out i guess its said heat under reflux

 

[Goku]

Check out this thread:
http://www.xtremepapers.com/community/threads/chemo-p5-tips.5917/
There's some notes and stuff in it that should prove useful. ^_^

Also, remember that paper 5 counts as 12% of your overall grade and paper 2 is 23%, so you need to make sure you really do your best in papers 2 and 4 as these are the ones that carry the highest weight-age. Hopefully, this way, you'll be able to make up for getting a lower grade in paper 5.

Hope I helped a little.

Thaaaankyooooooooooooooooou!!! :')
So if I messed up p1 ,and get good grades in p2 and p4 and p5 - can I get an overall A ?

 

[Paradoxical]

Thaaaankyooooooooooooooooou!!! :')
So if I messed up p1 ,and get good grades in p2 and p4 and p5 - can I get an overall A ?

No prob. ^_^

Yea, you should be able to, just make sure you do your best in 'em! I messed up my paper 1 and paper 3 last year but I still managed an overall A in AS chemistry. I'd say you need to be aiming for fairly high marks in papers 2 and 4. Best of luck, insh'Allah we all get amazing grades and I hope paper 5 is easy tomorrow because I am not at all prepared for it. :s

 

[Goku]

No prob. ^_^

Yea, you should be able to, just make sure you do your best in 'em! I messed up my paper 1 and paper 3 last year but I still managed an overall A in AS chemistry. I'd say you need to be aiming for fairly high marks in papers 2 and 4. Best of luck, insh'Allah we all get amazing grades and I hope paper 5 is easy tomorrow because I am not at all prepared for it. :s

Oh wow really?
thankyou,that gives me hope

Yeah,InshaAllah.
No chance of screwing up now.
Yeeah I hope so too,cos lol im not prepared for it either

 

[hihi]

can someone summerise all te rules how to find chiral molecule, please ?

 

[hassam]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s10_qp_51.pdf
q1 last part............how do we knw whether to take mole of acid or alkali

 

[JulyMei]

can someone summerise all te rules how to find chiral molecule, please ?

4 different atoms around a carbon.

 

[perkypearl]

can anyone explain me how to find moles in equilbrium ?? they ask us to fin intial moles at equilbrium moles finall moles

 

[IsaacNewton]

M/J/09 Paper 5. Q2, b
The graph. What will be the shape of the graph. They clearly say they have to be two lines.
The points plotted seem like a Cumulative Frequency curve....

 

[DragonCub]

can someone summerise all te rules how to find chiral molecule, please ?

Once you find a carbon atom that is connected to four groups different from each other, that carbon atom is a chiral centre.
Carbon connected to only three or even two groups cannot be a chiral centre.
In a moderately complex molecule, there could be more than one chiral centre.

 

[Utsav.]

how does the increase in the solubility with the temperature of a reaction make the reaction exothermic???

 

[terry jefferson]

can anyone explain me how to find moles in equilbrium ?? they ask us to fin intial moles at equilbrium moles finall moles

theyll most probably give the KC too.....so u equate the concentration to KC and find x.....then substitute x in your concentraions for the reactants and products and youll get your moles at equilibrium. hope u get it............it will be easier to explain if you gave the values.....

 

[perkypearl]

theyll most probably give the KC too.....so u equate the concentration to KC and find x.....then substitute x in your concentraions for the reactants and products and youll get your moles at equilibrium. hope u get it............it will be easier to explain if you gave the values.....

i am still confuse

 

[raamish]

j09 1d(ii)

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w09_qp_21.pdf
3a(iii) 3c
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w09_qp_22.pdf
3

Please help me out not much time left for me​

 

[fatima 007]

Can anyone pleaseeeeee help me? Please tell me where can i read about purification of copper? I dont have nay notes on this!

 

[Paradoxical]

Oh wow really?
thankyou,that gives me hope

Yeah,InshaAllah.
No chance of screwing up now.
Yeeah I hope so too,cos lol im not prepared for it either

Aha, yea, really! xD But I did really well in paper 2. I still remember how, after the practical, I was convinced I'd end up getting a C or something because it'd gone so awful. :s

Let me know how it goes tomorrow, hopefully we'll both be pleased.

 

[angelicsuccubus]

This one is impossible. Lead is not reduced at all in this reaction.

i found it on a chem balancin website

 

[Jaf]

Can anyone pleaseeeeee help me? Please tell me where can i read about purification of copper? I dont have nay notes on this!

Nothing much to it, really. The anode is made of impure copper, the cathode is made of pure copper. The electrolyte is aqueous copper sulfate. After some time the cathode gets bigger in size/heavier in mass because copper was deposited on the cathode.
This reaction happens at the anode:
Cu -----> Cu(2+) + 2e-

This is what happens at the cathode:
Cu(2+) + 2e- -----> Cu

Often, 'slag' will form in the container at the bottom. This will be the 'impurity' and may contain other metals, etc.

That's it!

 

[Jaf]

Good luck everyone!! I'm out.

I'm doing 31 tomorrow so PM me later tomorrow whoever wants to discuss the paper.

 

[Muhammad Asif]

can anyone explain me how to find moles in equilbrium ?? they ask us to fin intial moles at equilbrium moles finall moles

write the equation of the reaction first.....in a situation u will be given initial and final moles of a reactant or the product or change in moles in reactant or product... if u are given change in moles than do stoichometery from ratios(from the equation) to find the moles at equlibrium...