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.
Monday, 11 May 2009
Wednesday, 25 March 2009
S205: CMA-2
So - there is another computer marked assignment to do. There are 35 question to be done, and they vary a lot in format. Some you have to work out a number and type it in. Others require ticking boxes, and so on. These have their strengths and weaknesses. Firstly its a computer marking your efforts, although the questions are reviewed by the course team. This does mean you can sometimes get what you think is the right answer only to be caught out on a technicality, like typing 2.0 when it is expecting 2. Mostly though its pretty good at taking reasonable answers - but of course can't apply the same common sense a human can.
You generally get 3 attempts at an answer, unless its a true/false type one. A couple of them I got completely wrong. One was on the symmetry of SeOCl4 using VSEPR - which even after 3 attempts I still got wrong, and couldn't work out why. My tutor suggested some possibilities given I knew the answer (it tells you once you get it wrong). I also checked it out with a chemistry lecturer friend and she came to the same conclusion as I had. After taking it up with the course team they explained (after the deadline) why their answer was right, but eventually they zero'd out the question as it was rather ambiguous. Even given the answer I couldn't see how you could come up with a definitive structure based on just the course notes - there simply wasn't enough data to cover these weird edge cases. The trouble with issues like this is that I find it suddenly undermines my confidence. Its not a silly mistake, its something I've thought about and still got wrong. I suppose whatever doesn't fail makes me stronger, but in reality it tends to lead to a certain fear of similar questions.
The other question I got wrong I could eventually see I'd just made a silly mistake. Its a bit weird doing these things, you tend to get CMA blindness. For instance I'd take all the data given, do all the calculations and come up with an answer - I'd probably check it too - and then look at the screen and see if my answer was there. If it was, I'd tick it, if not then I clearly need to try again. However often you get one of these calculations where you end up doing a load of steps and then the final one is to multiply by 2 -- or is that divide by 2... after due consideration you decide its multiply by 2, see the answer is there, tick and go. Wrong answer. My immediate reaction is not to do any more work (because I'm lazy by nature) but to assume it was divide by 2, and the answer is there to, so tick that and resubmit immediately without rechecking things. Wrong again! This is where you're 3rd chance comes in, and where you should sit down and rework the problem again - rather than phoning a friend or asking the audience.
Anyway - that was the last of the two CMAs in this course.
You generally get 3 attempts at an answer, unless its a true/false type one. A couple of them I got completely wrong. One was on the symmetry of SeOCl4 using VSEPR - which even after 3 attempts I still got wrong, and couldn't work out why. My tutor suggested some possibilities given I knew the answer (it tells you once you get it wrong). I also checked it out with a chemistry lecturer friend and she came to the same conclusion as I had. After taking it up with the course team they explained (after the deadline) why their answer was right, but eventually they zero'd out the question as it was rather ambiguous. Even given the answer I couldn't see how you could come up with a definitive structure based on just the course notes - there simply wasn't enough data to cover these weird edge cases. The trouble with issues like this is that I find it suddenly undermines my confidence. Its not a silly mistake, its something I've thought about and still got wrong. I suppose whatever doesn't fail makes me stronger, but in reality it tends to lead to a certain fear of similar questions.
The other question I got wrong I could eventually see I'd just made a silly mistake. Its a bit weird doing these things, you tend to get CMA blindness. For instance I'd take all the data given, do all the calculations and come up with an answer - I'd probably check it too - and then look at the screen and see if my answer was there. If it was, I'd tick it, if not then I clearly need to try again. However often you get one of these calculations where you end up doing a load of steps and then the final one is to multiply by 2 -- or is that divide by 2... after due consideration you decide its multiply by 2, see the answer is there, tick and go. Wrong answer. My immediate reaction is not to do any more work (because I'm lazy by nature) but to assume it was divide by 2, and the answer is there to, so tick that and resubmit immediately without rechecking things. Wrong again! This is where you're 3rd chance comes in, and where you should sit down and rework the problem again - rather than phoning a friend or asking the audience.
Anyway - that was the last of the two CMAs in this course.
Tuesday, 10 March 2009
S205: Book 9 - Elements of the p-block
Oh no -its another vast book - 242 pages about lots of stuff - its information overload, and I'm not really sure what you are suppose to take away from this book. There seems far too much to learn, so in the end I just end up reading the book and hoping some of the concepts sink in ... hummm.
It starts off of, by looking at oxidation states and how you can work them out from various rules. That's not too bad.
The next chapter starts to look at acids and bases, and in particular extends the definition to Brønsted acids - which are compounds that can donate a proton or hydrogen ion.
So having just got the idea of a new type of acid, we have another new type in the next chapter - the Lewis acid. This is a substance that can donate a pair of electrons. Okkkayyy - just about getting that.
Next chapter is all about the chemistry of hydrogen - what it can do and how it can form hydrides and things like that. I'm sure there is some general message here but it seems like just a large number of different reactions.
Next we look at halides, and all manner of ways that the halogens can form compounds. Again a confusing number of different reactions.
After that - a real walk on the wild side as we look at those most unreactive of elements, the noble gases and the various compounds they can form. Its a bit like being told there is no Santa Claus that compounds of the noble gases can form compounds. I mean - the one thing you generally learn in chemistry is that compounds struggle to form bonds to make noble gas like electron shells. Then along comes xenon, and starts disrupting these well rehearsed truths.
After a brief foray into some trends in second and third row elements (which is also covered - better for me - in a dvd accompanying the book), we launch into group 3. Boron, aluminium and so on. Boron is plain weird, it eschews the eightfold way and is happy to make compounds with only a shell of 6 electrons. Its all rather disconcerting.
Then its time to look at group 4. Carbon, silicon and their ilk. It seems we've been doing precious little other than looking at carbon for most of this course, but here it is again.
Follow this up with a look at group 5 nitrogen, and phosphorous, and all they can do. Then its on to oxgen, sulphur and its pals.
Finally another look at trends and the book is done, except for a case study look at acid rain.
So much information, so many reactions - my head is spinning. How can anyone possibly remember a 10th of this stuff.
It starts off of, by looking at oxidation states and how you can work them out from various rules. That's not too bad.
The next chapter starts to look at acids and bases, and in particular extends the definition to Brønsted acids - which are compounds that can donate a proton or hydrogen ion.
So having just got the idea of a new type of acid, we have another new type in the next chapter - the Lewis acid. This is a substance that can donate a pair of electrons. Okkkayyy - just about getting that.
Next chapter is all about the chemistry of hydrogen - what it can do and how it can form hydrides and things like that. I'm sure there is some general message here but it seems like just a large number of different reactions.
Next we look at halides, and all manner of ways that the halogens can form compounds. Again a confusing number of different reactions.
After that - a real walk on the wild side as we look at those most unreactive of elements, the noble gases and the various compounds they can form. Its a bit like being told there is no Santa Claus that compounds of the noble gases can form compounds. I mean - the one thing you generally learn in chemistry is that compounds struggle to form bonds to make noble gas like electron shells. Then along comes xenon, and starts disrupting these well rehearsed truths.
After a brief foray into some trends in second and third row elements (which is also covered - better for me - in a dvd accompanying the book), we launch into group 3. Boron, aluminium and so on. Boron is plain weird, it eschews the eightfold way and is happy to make compounds with only a shell of 6 electrons. Its all rather disconcerting.
Then its time to look at group 4. Carbon, silicon and their ilk. It seems we've been doing precious little other than looking at carbon for most of this course, but here it is again.
Follow this up with a look at group 5 nitrogen, and phosphorous, and all they can do. Then its on to oxgen, sulphur and its pals.
Finally another look at trends and the book is done, except for a case study look at acid rain.
So much information, so many reactions - my head is spinning. How can anyone possibly remember a 10th of this stuff.
Saturday, 28 February 2009
S205: TMA-3
Time for TMA-3 - and a bit of a disaster for me, despite thinking I'd done it almost perfectly!
Question 1 was about molecular orbital theory, and drawing diagrams and putting electrons in for a molecule of PS. Most of this was fairly easy, except for the last part where you had to work out how it would decompose. Despite questioning my tutor, I couldn't grasp exactly what this was asking, and got almost no marks for this part. I'm still not much the wiser.
Question 2 concerned semiconductors and the doping thereof. Some more diagrams to be drawn and some theory to be expounded on.
Question 3 was about organic reactions, and mostly to do with carbocations and yet more stereo-chemistry. I don't think I have the patience to do some of these reactions, and it shows in the marks I get! Some of the latter part of the question was on synthesis techniques, and how to get from one compound to another.
Question 4 was full on synthesis. How to move around from one molecule to the next, what sort of thing you needed to add to it, and what conditions this might happen under and so on and so forth. I think I did ok on this one, but it was a struggle.
This TMA is probably the low point so far for me, as I didn't do nearly as well as I thought I would, and it sort of leaves you wondering if you understand the basics or maybe you're just not cut out for the subject. However this seems to happen in most of the 60 point courses I've done, so its probably just a psychological hump. I hope so!
Question 1 was about molecular orbital theory, and drawing diagrams and putting electrons in for a molecule of PS. Most of this was fairly easy, except for the last part where you had to work out how it would decompose. Despite questioning my tutor, I couldn't grasp exactly what this was asking, and got almost no marks for this part. I'm still not much the wiser.
Question 2 concerned semiconductors and the doping thereof. Some more diagrams to be drawn and some theory to be expounded on.
Question 3 was about organic reactions, and mostly to do with carbocations and yet more stereo-chemistry. I don't think I have the patience to do some of these reactions, and it shows in the marks I get! Some of the latter part of the question was on synthesis techniques, and how to get from one compound to another.
Question 4 was full on synthesis. How to move around from one molecule to the next, what sort of thing you needed to add to it, and what conditions this might happen under and so on and so forth. I think I did ok on this one, but it was a struggle.
This TMA is probably the low point so far for me, as I didn't do nearly as well as I thought I would, and it sort of leaves you wondering if you understand the basics or maybe you're just not cut out for the subject. However this seems to happen in most of the 60 point courses I've done, so its probably just a psychological hump. I hope so!
Wednesday, 25 February 2009
S283: Book 1 - An Introduction to the Solar System
Book 1 is a fairly weighty tomb, but about the size of the S282 books, and similar to the 2nd book in the course as it happens. Its 412 pages in total, and split into 9 chapters.
Chapter 1 is an introduction to the solar system. We briefly visit all the major bodies of the solar system in turn and look at the general layout of things. It gets you oriented into whats where and what will be looked at in the next few pages.
Chapter 2 looks at terrestrial type planets and their internal structure. There is a fair smattering of geology in this part, and stuff about tectonics and inner cores and stuff like that. There is also some parts on what happened over its life as the rocks were 'cooked' and changed.
Chapter 3 looks in depth at volcanism. So there is a lot about volcanoes and eruptions of lavas and what that can do to surfaces. It also considers cryovolcanism, where water and ice errupt in the more frozen worlds giving similar results.
Chapter 4 looks at planetary surfaces and in particular at cratering and what it can tell us about what has happened. We go into quite a lot of depth (NPI) on different types of crater and how they can be recognised.
Chapter 5 looks at plaentary atmospheres - for those lucky enoguh to have them. It also looks at clouds, and atmospheric motion, and the different layers that they tend to split into.
Chapter 6 looks at the gas giants, and what they're structure might be.
Chapter 7 is concerned with the more minor bodies of the solar system. So things like asteroids, comets, the Kuiper belt and even interplanetary dust.
Chapter 8 looks at how the solar system was formed, and what that was all about.
Chapter 9 ends up looking at meteorites and what they can tell us about what happened at various stages in its evolution.
So - that was quite a tour, but in some ways it wasn't as detailed as the earlier planets course I did. Many of the mechanisms we gone into in a lot more depth, but I didn't come out of it feeling I knew a lot more about the planets, but knowing a fair bit more about their formation.
Chapter 1 is an introduction to the solar system. We briefly visit all the major bodies of the solar system in turn and look at the general layout of things. It gets you oriented into whats where and what will be looked at in the next few pages.
Chapter 2 looks at terrestrial type planets and their internal structure. There is a fair smattering of geology in this part, and stuff about tectonics and inner cores and stuff like that. There is also some parts on what happened over its life as the rocks were 'cooked' and changed.
Chapter 3 looks in depth at volcanism. So there is a lot about volcanoes and eruptions of lavas and what that can do to surfaces. It also considers cryovolcanism, where water and ice errupt in the more frozen worlds giving similar results.
Chapter 4 looks at planetary surfaces and in particular at cratering and what it can tell us about what has happened. We go into quite a lot of depth (NPI) on different types of crater and how they can be recognised.
Chapter 5 looks at plaentary atmospheres - for those lucky enoguh to have them. It also looks at clouds, and atmospheric motion, and the different layers that they tend to split into.
Chapter 6 looks at the gas giants, and what they're structure might be.
Chapter 7 is concerned with the more minor bodies of the solar system. So things like asteroids, comets, the Kuiper belt and even interplanetary dust.
Chapter 8 looks at how the solar system was formed, and what that was all about.
Chapter 9 ends up looking at meteorites and what they can tell us about what happened at various stages in its evolution.
So - that was quite a tour, but in some ways it wasn't as detailed as the earlier planets course I did. Many of the mechanisms we gone into in a lot more depth, but I didn't come out of it feeling I knew a lot more about the planets, but knowing a fair bit more about their formation.
Next S283 Prev S283
Monday, 23 February 2009
S205: Book 8 - Separation, purity and Identification
Book 8 - and quite a thin one for a change. However the euphoria of that swiftly departs towards the end. Anyway, the first part is all about practical chemistry, something we don't do any of in this course, other than read about it!
We have some chapters on separation of products, by using suitable dissolving agents and the like goes with like rule. Then there is a chapter on how to find out how pure the substance you made is, and then some stuff about identifying the compound you've made.
Then, just as you think the book is about finished, we move onto IR spectroscopy and NMR. There is nothing written about this in the book, other than directions to work through a whole set of videos and computer aided learning on the accompanying DVD.
So there are a number of exercises to work through to find out what NMR and IR are telling you about things. After working through IR and getting the idea you can find some stuff out, the NMR comes as much more of a revelation as it gives you much more information in general.
Finally the book ends up with a case study on forensic science and what chemists can do to aid the search for truth.
We have some chapters on separation of products, by using suitable dissolving agents and the like goes with like rule. Then there is a chapter on how to find out how pure the substance you made is, and then some stuff about identifying the compound you've made.
Then, just as you think the book is about finished, we move onto IR spectroscopy and NMR. There is nothing written about this in the book, other than directions to work through a whole set of videos and computer aided learning on the accompanying DVD.
So there are a number of exercises to work through to find out what NMR and IR are telling you about things. After working through IR and getting the idea you can find some stuff out, the NMR comes as much more of a revelation as it gives you much more information in general.
Finally the book ends up with a case study on forensic science and what chemists can do to aid the search for truth.
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