Sunday, 21 January 2007

S103: Block 6 - Our world and its atoms, TMA-5

Block 6, and its firmly into chemistry, with a small detour into physics at the end.
In this block we start looking in much more detail about atoms and elements. There is a fair bit of history of the way things were discovered, how to balance chemical equations, molecular weights and stuff like that. I knew quite a lot of this already, but some of the details were quite fascinating.

How they worked out chemical formulas for compounds for instance, and molecular weights. There are also some nice videos showing chemical reactions. Everyone loves the alkali metals interaction with water - especially my children!

The TMA is solely about this block this time.
First question is all about hydrogen selenide, a compound not covered in the block. Using the rules and knowledge gained from the block though you can work out all the details. You also have to draw a set of chemical apparatus to produce a sample of the gas.

The next question is about chemical calculations on arsenic and some of its compounds. Molar calculations come into the fray here.

The final question is about the element Uuh - one that hasn't quite been discovered properly yet, though there is a placeholder for it in the periodic table. We have to extrapolate from knowledge of other elements what it would probably be like.

This is my best TMA in the whole course, and I scored 99 out of a possible 100 for it.
Its quite interesting how the whole marking thing goes. When you get to close to the maximum, its almost down to luck how you score. It is incredibly easy to miss off a unit, forget the right number of significant figures or something somewhere in the 4-5 pages of answer. I lost a mark in this one for not labelling a connecting tube in one of my drawings of chemical apparatus.

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