A-level Organic Chemistry

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Edexcel sounds so incredibly crap!
I did Chemistry with OCR and I can't remember having to do such work!
Mind you my grades weren't all that, but ah well.
 
But you had coursework, did you not? My friend is doing OCR ans has coursework. Cswrk has its own ups and downs... Really, I'd rather do these practicles than coursework.
 
Second chances...*sigh* indeed, lol. If only...

And yup, I do ocr too...and am kinda almost wishing I didn't, lol, since I've got a piece of coursework I should really be working on at this very moment...:exhausted
 
That reminds me of a C3 paper I should be doing now.

Just curious... You're an A-level student now, right? What subjects do you do?
 
I do maths, further maths, physics and chemistry (yup, a total science nerd, if it wasn't already obvious, lol...)

What about you??
 
OCR is by far the worst exam board for every subject!

and... I too have Chem coursework... which I haven't the foggiest idea how to start.
 
~Raynn~ said:
I do maths, further maths, physics and chemistry (yup, a total science nerd, if it wasn't already obvious, lol...)

What about you??
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Physics and maths are ok, but there's to much information in chemistry that you can't simply calculate.
 
Biology, Chemistry and Maths for A-level. Did English Literature for AS then dropped it. I couldn't deal with memorising quotes anymore.

Well, you're not a total science nerd unless you get excited when you hear people talk about LiAlH4 or vectors... Or integration. I know of one that literally jumps in the air and claps her hands at the mention of those.
 
~Raynn~ said:
I do maths, further maths, physics and chemistry (yup, a total science nerd, if it wasn't already obvious, lol...)
Click to expand...

I remember my Maths teacher saying that some people debate whether Maths is a science or an art. :skeleton:

Who in their right mind considers maths an art???
 
The Ruler said:
Biology, Chemistry and Maths for A-level. Did English Literature for AS then dropped it. I couldn't deal with memorising quotes anymore.

Well, you're not a total science nerd unless you get excited when you hear people talk about LiAlH4 or vectors... Or integration. I know of one that literally jumps in the air and claps her hands at the mention of those.
Click to expand...

Um.... I have a feeling that Rayn does get excited at the mention of integration. Am I right Raynn ? :p
 
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Lol, okayy...I must admit I do somewhat like integration...it can be fun...but there's nothing exciting about LiAlH4...and I detest vectors...

Maths, an art... hmmm, pure maths can look pretty cool at times, you know...and it's always fun "proving" 1=2...;D
I expect no-one to read through it, but this is just something I came across ages ago...

http://www.maa.org/devlin/LockhartsLament.pdf

NOT that I'm quite that crazy, just to be clear, lol...
 
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Help me answer this Raynn:

Magnesium sulphate is soluble in water whereas barium sulphate is almost insoluble. Draw an enthapy level cycle for a Group 2 sulphate to show how the lattice enthalpy and the enthalpy of hydration can be used to explain the difference on the solubilities of magnesium sulphate and barium sulphate.

It's the synoptics. I hate that paper. I could get up and get to my folder several feet away... But it requires much energy I'm not willing to spend. Anyway... What's an enthalpy level cycle?
 
The Ruler said:
Magnesium sulphate is soluble in water whereas barium sulphate is almost insoluble. Draw an enthapy level cycle for a Group 2 sulphate to show how the lattice enthalpy and the enthalpy of hydration can be used to explain the difference on the solubilities of magnesium sulphate and barium sulphate.

It's the synoptics. I hate that paper. I could get up and get to my folder several feet away... But it requires much energy I'm not willing to spend. Anyway... What's an enthalpy level cycle?
Click to expand...

My guess is it's what I was taught to be a 'Born-Haber cycle'. Have you done Hess' Law?? The enthalpy cycle is basically an application of that, and is used to find the lattice enthalpy, when all other energy values are known...does this kind of thing look familiar?... [NaCl Cycle]. Try looking up born-haber cycles if none of this rings a bell...

As for the differences in the solubility, I'm not sure about the enthalpies of hydration, but with lattice enthalpy... because the magnesium cation is smaller than the barium one, it polarizes the sulphate ion more strongly, distorting the anion so the lattice breaks up more easily. MgSO4 therefore has a lower (less exothermic) lattice enthalpy; it ionizes more readily in water, so is more soluble. This is the explanation that first comes to mind, but I should probably check...
 
How would I do this:

Solid magnesium sulphate contains water of crystallisation, MgSO4.xH20. 1.23g of magnesiun sulphate crystals were dissolved in distilled water and excess barium nitrate solution was added. The white precipitate of barium sulphate was filtered off, dried and weighed. 1.16g of anhydrous barium sulphate was formed. Calculate x.
 
Basicallyyy...

- You know the mass of anhydrous BaSO4 (Mr = 233.1), obtained from the hydrated magnesium sulphate used at the start, 1.16g. Use this the find the number of mols of BaSO4 formed. (mols = mass/Mr; you get 0.004976...mols)

- This is also equal to the number of mols of hydrated crystals you started with...and, you're given the mass of the crystals, 1.23g. Use these values to find the Mr of the MgSO4.xH20 crystals. (Mr = mass/mols = 247.166...)

- The Mr of anhydrous MgSO4 is 120.4...subtract this from 247 to find the Mr of the xH20 part to get 126.76...

- Finally, divide this by the Mr of water, 18, to get x = 7.0

Man, this is a rather uncomfortable reminder of the coursework I'm still supposed to be doing...thus far, I have the title - "Determining the formula of Hydrated Copper Sulphate*: Evaluation".
Hold the applause.

*And this is after about 10 mins of debating whether or not to say 'copper sulphate crystals'
 

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