Tuesday, 27 January 2009

S205: TMA-2

The second bit of coursework looms - and its name is TMA-2.
Four questions to tackle, based on books 4 and 5.

Question 1 is all about thermodynamics. You have to calculate a number of entropy, enthalpy and other things about substances. You also have to draw a diagram of a Born-Haber lattice energy diagram and work out lattice energy for GeI4 a substance.

Question 2 concerns kinetics. You have to come up with an general reaction rate equation and then it starts to drip in information that eventually allows you to solve it bit by bit.
You also need to use the computer program provided (kinetics toolkit) to plot a graph of the reaction rate.

Question 3 is about SN1 and SN2 reactions. You are presented with some reactions and told what they might produce, and from this you have to deduce if it is an SN1 or 2 type reaction. You then have to draw the reaction diagrams with curly arrows showing where the electrons are moving around. Then it goes on to get you to consider the enantiomers produced and which might be dominant.

Question 4 is similar to question 3, but with different molecules, and we are looking at elimination reactions rather than substitutions.

I managed to get completely wrong on the last one and follow it to its logical conclusion but starting from a false premise.

Thursday, 8 January 2009

S205: Book 6 - Molecular modelling and bonding

This book is a book in itself, in that for once it isn't split into sections and parts, but does basically what it says on the cover.
It looks at the theory of electron clouds and how bonds form between atoms. It goes into all the detail about orbitals and hybridisation. It looks at what happens to bonds between atoms of the same type, and between different types. It also has a quick look at what is happening in semi-conductors, which is a little bit of a detour, although there is a relationship I suppose.

The part I don't really follow is the whole bit about symmetry. I can see some of the symmetries, others are a little harder to spot. I'm not too sure why they are important though, and to what extent the rather complicated rules for classifying the different symmetries are useful.

Finally there is a case study that looks at drug design and how knowledge of the bonding sites can allow enzymes and drugs to be designed.

Chemistry seems increasingly to be a collection of complex categorisation rules and quite a bit of maths. The maths I can cope with, but there seems a lot to remember otherwise. Oh well, judging by the book count, the course is over half way through now!