OCR F324-June 2013 Chemistry

ok my method

6=number of carbon atoms
1= number of double bonds
3=is the the position of double bond

therefore,

hexan-3-oic acid

very good, nice method

thanks

Define:stereoisomer

Describe the steps that takes place in Nucleophilic addition

1)molecule with same structural formula but different arrangements of atoms with space, cis trans,

2) generation of the nucleophile, (a dipole being induced or something like NaBH4)

donation of a lone pair of electrons to the electron deficient carbon atom(or carbon with a positive dipole), which froms a dative covalent bond.

in aldehydes ketones, the carbon oxygen double bond then breaks leaving a sigma bond, the bondaing pair goes to the oxygen
which then donates a lone pair to a nearby water molecule or something hcl, forming dative covalent bond finally the oxygen hydrogen bond in water breaks

thanks

Define:stereoisomer

Describe the steps that takes place in Nucleophilic addition

after the nice jan paper, yeah :/

Yep and mention that an OH- is released as a product.

My turn do you have hard question

yeah but did you see how hard f325 paper was? i rekon both units are going to be average tbh!

no I haven't :/ damn, has anyone got the paper? atleast in june f325 wont be as hard then

ok my method

6=number of carbon atoms
1= number of double bonds
3=is the the position of double bond

therefore,

hexan-3-oic acid

very good, nice method

worst paper ever that jan 2013 f325, normally has 1-2 hard questions this one had 4-5 hard questions put everyone off guard, i was onset for an A* got a b wtf lol.

Could someone please explain nuclear magnetic resonance?

Nuclear spin+ resonance + chemical shift please.

Thanks

It states clearly in the spec you don't need to know the details of NMR.

You just need to be able to understand how to solve related Analysis questions with regards to Proton H+ NMR, and Carbon-13 NMR.

The only other details are when you have Nitrogen and another element which has a Broad NMR Peak, and the types of Deuterated solvents that you must add to get around this problem. I.e. D20. Then know the limitations and hence the benefits of using NMR and Mass Spec together.

But the little details won't help you get any Exam Questions right, as its not on the spec.

Surprised how I remembered all of that. *Pats myself on the back* - must have learnt it pretty well first time round, I'm looking forward to re-learning this now!

What did you get in Unit 4, I got a B with like 80% Raw Marks.

I wish I did higher, I rushed the whole paper in like 40 minutes. And thought I bossed it.

Such poor technique. Need like 54+ Raw Marks if I want that A*. Come at me brah

Haha, I know it's not in the spec and it stated that in the book, I just really still wanted someone to shed some light on to it, just for a more ample understanding, we are expected to know about chemical shift though, says in the examiners tip.

And to understand that, I feel that I need to understand nuclear spin and resonance. :/

Wow, this stuff is pretty challenging! :L

i got low a in it high boundaries man, but going to do so much better for both units im retaking trying to go for the A* in both modules :/ need to get like 130/150 and for f324 82/90

Yeah this chapter is a bit odd. Don't worry too much about the finite details. To understand NMR Properly you would have to be doing a 1st or 2nd year Physics degree. http://teaching.shu.ac.uk/hwb/chemistry/tutorials/molspec/nmr1.htm

Focus on this and no more: http://www.chemguide.co.uk/analysis/nmr/highres.html

My strongest topic in Chem 4 is probably Module 3 the resonance stuff, because I realised early on that there isn't actually much to learn in it, and you don't have to be a genius to get the questions right because its just logic based.

Mod 1 and Mod 2 are more revision ASWELL as practice.

This time round I will learn Mod 1 and Mod 2 more like I learn Maths, and try to generalise it as much as possible.

I.e. focus on the fact that Reactions all occur in organic chem because of functional group, which my Tutor last year tried to bang across to me. He told me to stop making it more difficult than it is, because again its A-Level and not university level.

Apart from some necessary details, you just have to understand the problem solving approach to most questions.