ocr a f325 revision thread

It was really hard, especially the last question! My teacher was like that's the hardest paper she has ever seen in her life on that unit. And there was couple of application question, I got the paper with if you want it ??

Asking each other questions?

Yeah go on then

Define:Lattice Enthalpy (2)

the energy change when 1 mol of an ionic compound forms from its constituent gaseous ions under stp.

What is the ionic equation of the reaction between iodine and thiosulfate ions?

Could anyone show me how to answer this question step by step , I can get the correct products and reactants but cannot understand the balancing :

Construct the equation for the oxidation of acidified iron (ii) ions by oxygen.

This is the answer : 4Fe^2+ + O2 + 4H^+ --> 4Fe^3+ + 2H2O

First step write out a basic equation:

H+ + Fe2+ +o2 ->Fe3+ + H2O
Then balance the oxygens so a 2 in front of the H20. Then balance the hydrogen ions with a 4. You then know oxidation of Fe is +1, but the reduction of oxygen is -4 so you neeed a 4 in front of both the Fes.

Doing the Final Module.

Has any one seen any Exam Questions on the Optical Isomerism of Complexes ???? Like Drawing out?

They seem quite hardcore not sure they would show up in an exam question??

If its drawing out complexes as either optical or stereoisomers then they are asked for and they aren't that hard really, just need to remember the few little alterations between them.

Practice makes perfect though


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Ah okay cheers. Think I found a trick. For the Cis-Trans one its straight forward enough 90degrees-180 degrees Then for the Stereoisomers, you can just draw out one, and then remember the other one is just a "mirror" image, so reflect it.

Well I hope that will work. I was supposed to finish my D1 Papers and Do a Chem 5 Specimen Paper today. Only did 1/4 Papers D1 argh.

Why am I taking so long. Need to start revising for the subject I am going to do the night before. My brain just wasn't clicking for Chemistry for like 3 hours.

Yeah those are the tricks I've read about so I'll just be doing that too, although the hardest part will be determining whether a complex will have a square planar strcuture or a tetrahedral one, but they should give us clues in the question I hope

Well don't panic and just try again tomorrow, maybe a break will be good as I know that D1 papers can be extremely tedious and draining, at least they were for me.

The questions in this paper are so nasty. One of my classmates told me she saw a 20-marker! The max you would get previously was like 12 marks but even that was a juicy NMR question that was satisfying.

Edit: reason for negs?

They are boring as hell. Today's one was satisfying. The exams on the 17. I just want my teacher to hand me all my work back by at Least Friday the 10th like a week before. Think I can get an A* in it, but someone on this Forum reminded me that it doesn't mean much if I don't do the same C3/C4.... -___- It was a very good point.

Square Planar....wait what.... These shapes confuse me slightly! You seem much further in Chem 5 Revision than I am haha keep it up mate.

I need to get all the Papers Done for Chem 5 by like the 21st. Apparently we have Half-Term which is annoying. I really pray the Teachers are in school so they can mark my work!

Well I'm the same with my M1 exam but I'm just remaining calm and only doing 1-2 papers a week although this might increase slowly increase as these days pass by, but yeah I agree that doing better in C3 and C4 is definitely better than D1.

Its just a different a different structure which has a 90 degree bond angle which is normally present in cis-platin and also in the question the clue will be that the complex produces stereoisomers so you know it can't be tetrahedral and therefore can only be the square planar structure.

Yeah I'll be seriously picking up my revision when it gets closer but after doing a past paper the questions all seem quite similiar, if not routine slightly. Just keep at it and you'll get what you want to.

There is soo much to remember.. I don't mind the calculations, but the parts on ligands/transition metals etc is really difficult to remember all..