Chemistry: Post your doubts here!

[Rahma Abdelrahman]

Var

iant 41

Are you sure it was V1? Because I am sure that paper was TERRIBLE!

 

[Namehere]

Couldn´t we get a more difficult paper...? Paper 4 variant 1, my goodness... Will lose minimum 10-12 marks.

 

[AbbbbY]

I had a couple of friends come out of the paper claiming paper was extremely easy and all that
They didnt even know that to prove that Sn and Pb react with oxidising and reducing agents differently, we had to quote Standard Electrode Potentials
They just wrote since the +4 oxides are less stable down group four and stuff
Paper was easy but only for those who knew syllabus inside out.
So dont be scared guys
GT wont be that high
There will be hardly any 'shocking' grades
If you did good
You will get your just reward

By shocking, I meant, currently everyone I ask is already placing themselves at A* given the paper.

And yes. This was a common mistake. A lot of people couldn't tackle this question OR the part succeeded it, which asked for oxidation and reduction equations. Q1a was troublesome for a lot of people too, surprisingly. I'm not going to name the questions here for the 24 hour's sake.

Organic conditions messed with a lot of people, as did the last 2 parts of applications. But, all in all, IMO if someone had studied conceptually and not just by the past paper question types, it was a pretty easy paper.

 

[A star]

Can KI be used as a reducing agent in Sn reaction?

i used it too , it can be

 

[A star]

By shocking, I meant, currently everyone I ask is already placing themselves at A* given the paper.

And yes. This was a common mistake. A lot of people couldn't tackle this question OR the part succeeded it, which asked for oxidation and reduction equations. Q1a was troublesome for a lot of people too, surprisingly. I'm not going to name the questions here for the 24 hour's sake.

Organic conditions messed with a lot of people, as did the last 2 parts of applications. But, all in all, IMO if someone had studied conceptually and not just by the past paper question types, it was a pretty easy paper.

lol people had so many silly answers that made me laugh though. but it was atleast not difficult

 

[unkidd]

can someone after 24 hours write all the answers and explain me how we had to do the Ph question after 24 hours

 

[Busy Buddy]

Dear p4 varient 1 friends, how was the paper today?
Mine went too bad
Don't know why are most of my exams going too bad, although had been working hard.
Is there any chance to at least pass chemistry exam if p4 went toooo bad? Need some help & hope.

 

[Rahma Abdelrahman]

Dear p4 varient 1 friends, how was the paper today?
Mine went too bad
Don't know why are most of my exams going too bad, although had been working hard.
Is there any chance to at least pass chemistry exam if p4 went toooo bad? Need some help & hope.

I messed up the paper as well!

 

[Manobilly]

Dear p4 varient 1 friends, how was the paper today?
Mine went too bad
Don't know why are most of my exams going too bad, although had been working hard.
Is there any chance to at least pass chemistry exam if p4 went toooo bad? Need some help & hope.

it was very tricky .Lots of drawings

 

[Manobilly]

I messed up the paper as well!

InshaAllah everything will go well

 

[Eztair44]

So Whaddya guys think'll be the Percentile of this Paper?

 

[Rahma Abdelrahman]

InshaAllah everything will go well

I hope so.
In shaa Allah!

 

[Hinafatima]

Hi everyone
I've started a site which will provide you with solved papers showing all the steps in the working and with useful tips on the side. The best part is that when you look at a solved paper, you can look at commonly made mistakes and learn from them.
Please do check it out!
https://sites.google.com/site/fromatoscom/home

Hi!, is it only for 2012 and 2013 or r u going to add for other years too?? thanks a lot

 

[hope4thebest]

For starters, Lattice Energy can be either positive or negative. Depending on wether youre talking about bond breaking or bond formation. However with reference to how the Born Haber Cycle was formed in that question, Lattice Energy was exothermic.
Secondly, the electrode potential was -0.19V
Reason?
The reduction potential of 1 mol/dm3 was -0.13
Pb2+ + 2e <----> Pb -0.13V
Since the concentration is less than 1 mol/dm3, the equlibrium will shift to the left and think about it this way. It will be even more difficult to reduce so reduction potential will further decrease
Hence 0.19
Now for graph
first of all graph ended at 12.5. Final pH was 12.5
Inital ph was I think, if I remember correctly, 2.8
There would be a very small steep graph initally as the acid was weak
Then a buffer would be formed so slow rise in pH until 10 cm3
Steep vertical portion at 10 cm3
End point above 7
Finally pH would be 12.5
I found Question 1 Part 2 a little difficult
Didnt know what to write
Also the question where he converted -CONH2 to -CH2NH2
I thought about it
Hes reducing
So I just used LiAlH4, not NaBH4, since NaBH4 since it is weak. And I was right.

lattice energy is always exothermic as only bond formation takes place

 

[AnujaK]

No I'm gonna post more I think there are already others though

Hi!, is it only for 2012 and 2013 or r u going to add for other years too?? thanks a lot

 

[istudent]

can anybody who gave 9701 p42 tell final [OH-] and final pH

 

[sumeru]

can anybody who gave 9701 p42 tell final [OH-] and final pH

0.033 and 12.5

 

[omarjaved619]

Drawing with pencil is optional right? Or is it a must?

 

[istudent]

0.033 and 12.5

can explain how?

 

[hope4thebest]

0.033 and 12.5

same same