Thursday, 28 May 2009

S205: TMA-5

Last but one TMA. Not one I'm looking forward too as much. Its got essay like things in, and its so easy to lose marks in these. Oh well, after all the biology essays I've done, and skating quickly over the archaeology ones, I ought to be used to this sort of thing, so hey ho.

Question 1
In this one, you have to prepare an overhead transparency for a 1 minute talk. Of course almost no one uses overheads these days, they use powerpoint or similar. Gone are the days (hopefully) of getting acetates shrink wrapped around the photocopier drums. You have to prepare the overhead, on the subject of "The use of VSEPR to predict the structure of tellurium tetrachloride". You then have to write a script that when read aloud will take 1 minute to read in a normal voice and taking breaths etc. Apparently in some previous versions of the course, you actually had to record the talk and post a tape with it on, but thankfully that isn't required now. Your tutor has to read it and decide if you are within the time limits. You can annotate the script a little with markers to show where you are pointing to on the slide.
Anyway, not too bad a question - the topic is fairly striaghtforward, and a few graphics help spice up the slide.

Question 2
This is about book 9 - p-block materials. You have to identify an element given a few facts about its appearance and its reactions with flourine. Then a bit about its oxidation states, and then its reactions with acid and alkalis.

Question 3
Some entropy sneaks back in, as you have to compose a formation reaction for BCL3. Then draw a lewis structure for it.
Thats followed up by a full blown thermodynamic cycle for the construction of it so you can work out the molar enthalpy. Finally an equation for the formation of BCL3 from boric oxide and phosphorous pentachloride.

Question 4
More identification of solids and solutions based on some reactions. Some reactions are described and you have to predict what will be formed, then these in turn react and so on. Of course if you get step 1 wrong, your a bit lost for the rest of the question.

Question 5
Its essay time. "The chemistry of bromine can be predicted from its position in the Periodic Table". A report of 600 words explaining this. You can include graphs, diagrams, pictures, tables etc, and I throw in quite a few of these as it helps give me something to do rather than just writing words, and it also breaks up the structure a bit. Even a picture of dear old Dmitri Mendeleev helps give it a bit of colour.
You have to do all the usual stuff, introduction, conclusion, references etc. Anyway, after a lot of tinkering with it, I get something I'm not altogether happy with, but can't see how to improve it in the time and space available.

So - just one more to go, then the exam looms on the horizon.

Tuesday, 19 May 2009

S205: Book 10 - Mechanism and Synthesis

Book 10 - the last real book. There is a Book 11, but its more of a pamphlet and discusses how to write essays and make presentations and stuff like that.

Anyway, Book 10 is all back to organics and synthesis.

First there is a whole section on carbonyl compounds and reactions - those things with a C=O in them somewhere. I guess you either like this sort of stuff, or not. I'm rather less than impressed with it all, although the rules seems straight forward there seem to be a lot of them.

Then the next section is all about organometallic reactions. Grignard reagents. Despite not really knowing how these are made, they seem awfully useful for glueing bits of molecules together.
It starts with magnesium compounds, then we move through into sodium, lithium and copper compounds. Then it finishes up with organoboron.

Section 3 looks at radical reactions - where you get compounds with single electrons lieing around. These use to be so rapid and violent to be unusable, but recent times they have found ways of taming them to make a useful way of doing things.

Section 4 is about retrosynthesis mostly. So knowing what you want to make, how can you work backwards to find a way to make it from everyday molecules. Basically there is no right way or wrong way, but some rules help you to break up compounds to make it easier. It seems a combination of science, experience and a touch of art.

The last section looks at biosynthesis, which rather puts chemist in the shade. Making complex molecules at room temperature and pressure without breaking a sweat.

Finally, there is a case study on polymers.

Phew - all done - finally got to the end of what has been a long course squeezed into what seems too short a time!

Tuesday, 12 May 2009

S283: TMA-1

Well compared to the chemistry I'm doing alongside this, I find this TMA reasonably easy. Possibly too easy as I get a less than expected mark for it. That will teach me!
Lets see - what does it have in store?

Question 1 is about the formation of the solar system. When it formed, why rocky planets are in the inner and gas giants in the outer. Stuff about ring systems and density, and the asteroid belt. Not too bad for a start.

Question 2 is geology. What the structure of the earth is, what the layers are, how they are defined and stuff like that. Some bits on mineralogy and seismic data, and rounded off with xenoliths and what they can tell us about the structure.

Question 3 looks at various moons, and gets you to fill in a table. How old is the surface of each, what if any caused the resurfacing, and what was it made up of. Then you are given data about two imaginary satellites, and asked to work out from density and other information what sort of body they are likely to be.

Question 4 is about volcanism and cryovolcanism. What basalt is so common, what makes it so and so on. More geology...

Question 5 is interesting, as you are given a picture of part of the moon, and have to work out various dimensions of the craters pictured, and then determine if they are simple or complex craters. I found acrobat reader has a great tool for this sort of measuring. Then you have to make various observations and hypotheses about the craters such as age and relative order.

Monday, 11 May 2009

S205: TMA-4

Another TMA - and they are coming thick and fast at this point. Two TMA's due in the same month! This TMA is a bit of a monster, but turns out to get my best mark so far, so maybe something is sinking in - although I suspect its just how it goes.

Question 1 is about analysis. You are given some weights of elements found in a compound and asked to work out the empirical formula for it. Its really not too difficult, as its sort of like the S103 stuff, but a bit more complex. A nice surprise after some of the nightmare questions!

Question 2 is all about identifying struture. Youy are given IR and NMR spectroscopy data, and based on this and the molecular formula, you have top work out what the structure is. I find the NMR pretty good to do. The IR is a little vague, but you can answer it pretty much just from the NMR data, and use the IR for confirmation.

Question 3 is NMR from the other direction. Given a particular structure, you need to predict what NMR peaks and troughs it should give you. Its not too bad - once you get the idea of carbon equivalence.

Question 4 is looking at oxoacids, and working out their strengths. Its fairly straightforward if you can relate it to Paulings rules and coefficients.

Question 5 is to write an essay plan for the essay that has to be written for TMA-5. An essay - in chemistry, I never thought I'd see the day! Oh well...

As I said, not a bad TMA - which I think is more down to the absence of complex organic reactions than anything else.