ocr a f325 revision thread

Reply 3440

Nuna

1

so I still don't get Q63) jan 2013??? someone help pls....

Reply 3441

Brad0440

Original post by AFC_123456789

Hey thanks for the reply. So it has cis-trans but NOT optical isomerism right?

And i mean does chloride donate lp to platinum. The 2N atoms obviously do but do the 2 chloride as well? Thanks man

Oh yeah, sorry, I meant 'no, it *doesn't have optical isomerism'. :s-smilie:

Oh right, yeah the chloride ions also donate one lone pair to the platinum each (all ligands must donate at least one lone pair to the central metal ion to be able to form the coordiante/dative covalent bond).

Reply 3442

kuku2013

Original post by Nuna

so I still don't get Q63) jan 2013??? someone help pls....

which question?

Reply 3443

AFC_123456789

2

Original post by Brad0440

Oh yeah, sorry, I meant 'no, it *doesn't have optical isomerism'. :s-smilie:

Oh right, yeah the chloride ions also donate one lone pair to the platinum each (all ligands must donate at least one lone pair to the central metal ion to be able to form the coordiante/dative covalent bond).

No worries. So are there a total of 4 ligands in cis platin?

Reply 3444

beccac94

19

Original post by Nuna

so I still don't get Q63) jan 2013??? someone help pls....

I assume you mean question 6e) Basically you write out equations for both cr3+ and x, the x equation is x->x2+ +2e-

You combine the 2 equations and you get the mole ration. The you work out the moles of chronium by doing 1.456/52 to get 0.028. As the mole ratio is 3:2 the moles of X are 0.042.

You can then work out the mr by doing n=m/mr and you get the answer to be Mg :smile:

Reply 3445

Brad0440

Original post by AFC_123456789

No worries. So are there a total of 4 ligands in cis platin?

Yep, two NH3 and two Cl-.

Reply 3446

kimsiclez

12

Original post by eggfriedrice

In Jan 2013 q8) ci. There is no clear color change at the end point but why in the mark scheme talk about the colours at the START of the reaction?

MnO4- is purple and Vn+ is violet, however surely only the ending point colours would matter which are yellow and pale pink.

Because they#'e both purple it would be difficult to tell when the end point has been reached in the first place.

Think about it.

You're adding a purple solution to a purple solution and looking for an end-point which is a mix between pink and yellow. The colours are all too similar to make a clear distinction of an end point.

Hope that makes sense!

Reply 3447

AFC_123456789

2

Original post by Brad0440

Yep, two NH3 and two Cl-.

You're a top guy! Good luck pal

Reply 3448

Brad0440

Original post by AFC_123456789

You're a top guy! Good luck pal

Thanks, you too!

Reply 3449

bill7202

can someone tell me how to do June 12 q3 cii?

Reply 3450

beccac94

19

Original post by bill7202

can someone tell me how to do June 12 q3 cii?

Mg2+ has a smaller ionic radius and greater charge than Na+ (Remember when it comes to differences in charge you have to mention BOTH ionic radius and charge) Mg2+ has a greater charge density than Na+, Mg2+ as a greater attraction for water molecules than Na+.

Its like the same thing I write for all of these exams except the ions are different.

Reply 3451

bill7202

Original post by beccac94

Mg2+ has a smaller ionic radius and greater charge than Na+ (Remember when it comes to differences in charge you have to mention BOTH ionic radius and charge) Mg2+ has a greater charge density than Na+, Mg2+ as a greater attraction for water molecules than Na+.

Its like the same thing I write for all of these exams except the ions are different.

i think you're looking at a different question, june 12 q3 cii is a buffer solution question

Reply 3452

beccac94

19

Original post by bill7202

i think you're looking at a different question, june 12 q3 cii is a buffer solution question

Ohhhhh I completely misread that question I thought it was Jan 13, I was still on an earlier comment :tongue:

Don't really feel like I needed to be negged for that though :/

Reply 3453

needtosucceed=)

10

I'm off now good luck everyone!!

Reply 3454

Mastermind2

1

Did this paper turn out to be a lot nicer than the Jan 13 paper?

Reply 3455

alow

19

Original post by Mastermind2

Did this paper turn out to be a lot nicer than the Jan 13 paper?

Much easier.

Posted from TSR Mobile

EDIT: Woah whats with the hate? Nobody can deny that it was so much easier than January's, that paper was horrible!

(edited 10 years ago)

Reply 3456

jess_m94

12

How does everybody think it went? I thought it was challenging but I think I've done well!

Reply 3457

alow

19

Original post by jess_m94

How does everybody think it went? I thought it was challenging but I think I've done well!

I thought it went really well, what did you (or anyone) get for the last part of the last question?

Reply 3458

Yemiisii

Original post by jess_m94

How does everybody think it went? I thought it was challenging but I think I've done well!

Some questions were easy but the last question ... :frown:

(edited 10 years ago)

Reply 3459

Tendael

I thought it went well ish, but I still found it a hard paper, if that makes sense. I'm not exactly jump up and down happy about the paper but I got through it. Easier than Jan 2013, harder than June 2012, imo.

ocr a f325 revision thread

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