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OCR F324-June 2013 Chemistry

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I'm sure it was 36/40 for an A last year for A2 level and yeah, you've got some marks to work with and I'm sure with enough work it can be achieved you just need to want it enough and put all the time into it, best of luck :smile:

48 UMS is an A which is 36.

42 UMS was a B which is 32 Raw marks/

Reply 1121

Zaphod77

Original post by Better

Is that an A*, please help me.

Give me some wisdom.

Well, A* is made up of an average of the 2 A2 exams and the coursework, but it puts me well on my way! I was happy :smile:

Haha, wisdom and me don't often go together :tongue:

I can say don't panic? I think the main thing with Chemistry is they can throw in some real curveballs of questions, but you've just got to get in the right mindset and think about how you've been given all the information and skills you need, what are they asking and how can I apply it? If you panic because it's a new question, you're not going to get the marks. I'm sure you'll be fine, just relax and enjoy the challenge!

Reply 1122

MathsNerd1

Original post by Better

48 UMS is an A which is 36.

42 UMS was a B which is 32 Raw marks/

Okay so you can only lose 12 more UMS if its going to be the same grade boundaries for practical as last year, that's pretty much 57/8-60 and 96/97-100

Quite a task if you ask me but prove me wrong :biggrin:

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Reply 1123

Better

Original post by MathsNerd1

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UMS doesn't work like that. It is not Linear. It is usually a Tailed off Curve.

Hence some years 95 Raw Marks = 150 UMS. Which my teacher in my old school explained, he was one of the people who worked closely with the Examiners.

My current Teacher should have just told us what to do, but all I can focus on now is getting the grades.

If you can get a graph to show me why I'm wrong then great, but for example in Physics, a friend got 90% Raw Marks and the UMS Skewed him to 100% UMS wise (150UMS)

Reply 1124

MathsNerd1

Original post by Better

I understand what type of graph the UMS conversation takes however I'd imagine that there are quite a few students out there that get all the marks, it just depends on the calibre of students taking the exams and lately they've constantly been increasing in their marks, but yeah there are always only a few minority getting the very top marks. :smile:

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Reply 1125

D4rth

Why has this thread gone quiet? Otrivine has disappeared, no wonder its quiet :P

How's everyones prep going? I need to start proper revision yet and learn the details but I know a good outline of the unit.

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Reply 1126

otrivine

Original post by D4rth

I am back

Reply 1127

D4rth

Original post by otrivine

I am back

:O where did you go?! I was beginning to get worried!

Over the past few weeks I've become in love with chemistry more and more! Organic is so fun.

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Reply 1128

otrivine

Original post by D4rth

:O where did you go?! I was beginning to get worried!

Over the past few weeks I've become in love with chemistry more and more! Organic is so fun.

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good nice to hear that!! we will soon begin with revision any ways we still have a month left
and thanks for caring about me :biggrin:

very nice of u

Reply 1129

Zzzyax

Gas chromatography, with a liquid stationary phase,
Can someone explain why greater solubility of the sample reduces retention time?
http://www.ocr.org.uk/Images/61007-mark-scheme-unit-f324-rings-polymers-and-analysis-january.pdf

And can someone explain why greater solubility in the liquid stationary phase means a high retention timehttp://www.chemguide.co.uk/analysis/chromatography/gas.html

Spoiler

(edited 10 years ago)

Reply 1130

D4rth

Original post by Zzzyax

Gas chromatography, with a liquid stationary phase,
Can someone explain why greater solubility reduces retention time?

And can someone explain why greater solubility in the liquid stationary phase means a high retention time

Spoiler

Didn't that contradict itself? First you said greater solubility = lower retention time, then you said greater solubility = higher retention time.

But if it has greater solubility in the liquid phase this means it will move up a lot quicker, same rate as the thing its dissolved in.

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Reply 1131

reneetaylor

Do you know when you have to analyse a spectrum, for example NMR. What are the main things you include when analysing/identifying the compound present? It would be really helpful if someone could explain this in a condensed fashion, 'cause I've looked at the mark scheme, but still finding it a little difficult to remember what to include.

Reply 1132

Zaphod77

Original post by reneetaylor

Ok, NMR: (1) How many peaks does it have? From this, how many Hydrogen or Carbon (obviously depending on which type of NMR it is) environments are there? If it's Proton NMR, does a peak disappear when added to D2O? (2) Does it have splitting (again, proton) - n+1 rule, how many Hydrogens are therefore on the adjacent Carbon? (3) Chemical shifts. What bonds do the chemical shifts correspond to? Don't forget units (ppm). (4) Integration Trace. Ratios of Hydrogens in each peak? (5) Finally, bond it all together in a logical format. Check with all the data afterwards, but I think that's it! Good luck!

Reply 1133

Zaphod77

How did everyone's coursework go? There was a heck of a lot of conversation on it, but I never heard how anyone did - was everyone happy? :smile:

Reply 1134

Zzzyax

Original post by reneetaylor

Proton NMR spectrum analyse:
Chemical shift value - to identify the type proton environment
Number of peaks - number of different proton environments
Splitting patterns - number of protons attached to adjacent carbons (excluding NH/OH) remembering n+1 rule
Peak Area - area is proportional to number of protons in that environment
(Addition D2O solvent - sometimes added, OH/NH peaks removed)

Carbon - 13
Same except, no splitting, peak area, addition of D2O

IR
Type of bond present e.g. C=O, O-H
then state the value of the wavenumber
ignore fingerprint region

Mass spectrometry-
look at molecular parent ion, M+ (unfragement ion, peak furthest to right), its m/z value is equal to the molecular mass of the molecule, (assuming single ionisation, no isotopes present)
fragmentation patterns give structural details e.g. peak at m/z = 15 is probably CH3
always write down what the base peak is(largest peak)

(edited 10 years ago)

Reply 1135

Zzzyax

Original post by Zaphod77

How did everyone's coursework go? There was a heck of a lot of conversation on it, but I never heard how anyone did - was everyone happy? :smile:

i got 34/40 coursework mark, f325 was 144/150 UMS, can someone do calculations to see what i need for A* overall

Reply 1136

reneetaylor

Original post by Zaphod77

Original post by Zzzyax

Proton NMR spectrum analyse:
Chemical shift value - to identify the type proton environment
Number of peaks - number of different proton environments
Splitting patterns - number of protons attached to adjacent carbons (excluding NH/OH) remembering n+1 rule
Peak Area - area is proportional to number of protons in that environment
(Addition D2O solvent - sometimes added, OH/NH peaks removed)

Carbon - 13
Same except, no splitting, peak area, addition of D2O

IR
Type of bond present e.g. C=O, O-H
then state the value of the wavenumber
ignore fingerprint region

Mass spectrometry-
look at molecular parent ion, M+ (unfragement ion, peak furthest to right), its m/z value is equal to the molecular mass of the molecule, (assuming singe ionisation, no isotopes present)
fragmentation patterns give structural details e.g. peak at m/z = 15 is probably CH3
always write down what the base peak is(largest peak)