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My S216: Environmental Science course materials have arrived! Cue much rejoicing, general study planning, and a little list-making.

A brief aside on the topic of world maps:

Among the six books and the DVD pack was also a wall map of the Earth's surface. It's the Mercator projection, which has always bothered me. People's sense of geography is not based upon fact, but upon the Mercator map, and has been ever since it was first produced in 1569.

Representing a spherical object on a flat surface is always going to present problems, but the Mercator projection is not even close to being area accurate... Africa is frickin' huge. MASSIVE. As is South America. The main problem with this map is that the further the land mass is from the equator, the more its size is distorted. Thus, Greenland becomes a similar size to Africa.

However, in 1855, a clergyman named James Gall produced his own version of a map of the world, known as the Gall-Peters Projection. This has its drawbacks, too, but the areas represented are much more accurate. See - the northern hemisphere is puny in terms of landmass size compared to the south:

Back to the books:

Anyway. That's enough of maps (although I LOVE maps - if anyone wants to buy me antique maps, feel free).

The first block of S216 is a virtual field trip to the Teign Valley in Devon, and is DVD based. Then we're on to the books, which sound very interesting indeed...

Book 2: Air and Earth.

Part One - Air: We'll be looking at the atmosphere. It's cold outside, and there is an atmosphere. I'm all alone, more or less. Then there's the weather, and weather observations. Followed by the ins and outs of the atmosphere, and the global weather machine including ocean circulation and that pesky El Niño.

Part Two - Earth: Comprising rocks and minerals; igneous rocks; metamorphic rocks; fragmentary rocks; and the weathering of rocks and minerals. Then there's an introduction to soil - what it is; soil ecosystems; and soil processes and properties in the environment. I've got to be honest; this section doesn't sound so interesting...

Book 3: Water and Life. This is quite an alarmingly thick book.

Part One - Water: All types of water. What happens to rain? Ground water; a journey down a river; and the hydrological cycle. I like water. I'm reading a biography of water at the moment, and it's bloody fascinating. Water is strange stuff; it doesn't obey the usual laws of liquids. There is nothing as sweet as water when you're really, really thirsty.

Part Two - Life: Vegetation patters; resources to support life; and ecological dynamics. This is one of my areas of interest because I am a tree-hugging hippy who wants to save the world, one turtle at a time.

Book 4: Landforms and Cycles. This is a more reassuringly thin book.

Part One - Landforms: A bit of physical geography, which I loved at school, and which has stayed with me throughout adulthood. The way the Earth's roots works fascinates me. So we'll start with plate tectonics and an introduction to landforms, looking at lithology, and how water shapes the landscape inland and at the coasts. Then we look at ice, and wind, and finally landforms in space and time.

Book 5:

• Extreme weather
• Atmospheric chemistry and pollution
• Wetlands and the carbon cycle
• Cryosphere

Book 6:

• Oceans and climate (this one, I'm looking forward to)
• Water quality
• Eutrophication
• Acid rain

Book 7:

• Grasslands
• Tropical forests
• Biological conservation

Books 5, 6 and 7 are going to interest me particularly. This is a beast of a module, and I'm under no illusions as to how much work I'm going to need to put in. Structuring my life is going to be incredibly important over the next few months, so that I have time to spend with my husband, my friends and my family - not to mention the me-time that will be spent doing yoga and pole dancing.

But last year was fiercely busy, and I enjoyed it immensely. So I'm not fazed; and in fact, I can't wait. Bring on 2012. I'm ready for you.

I am no longer afraid of moles! No, not the little furry buggers that make a mess of your lawn. The once-frightening, but now benign, number used in chemistry so that your head doesn't explode due to excess zeros.

A mole - also known as Avogadro's number - is 6.02 x 10²³ "things". So, one mole of oxygen atoms contains 6.02 x 10²³ atoms. That's quite a large number. So large, that most people can't get their heads around it.

Here's an analogy: one mole of marshmallows would cover the United States of America to a depth of around 6,500 miles*. That is a LOT of marshmallows.

One mole of moles (the little furry buggers this time) would, if placed end-to-end, stretch 11 million light years, and weigh almost as much as the moon.*

Water flows over Niagara Falls at about 650,000 kL (172,500,000 gallons) per minute. At this rate it would take 134,000 years for one mole of water drops (6.02 x 10²³ drops) to flow over Niagara Falls.*

Anyway, enough analogies. Suffice it to say, it's a remarkably large number. Far too large to do anything practical with. So, chemists use the mole as a form of shorthand. At school, I hated chemistry specifically because of moles; I just couldn't get my head around it.

So it was with a sense of trepidation that I approached Book 4: The Right Chemistry.

My fears, however, were unfounded. I'm really, really, enjoying this book! The maths tackled so far has really helped to beat back the terrors of Very Large Numbers, and the book is great at explaining difficult concepts in simple terms.

I do think it helps that I am reading We Need to Talk About Kelvin when I'm not studying. This, too, is a cracking book that manages to explain extremely complicated ideas in layman's terms. Doing a bit of reading around the subject definitely helps to seal ideas into your mind, and allows them to take hold.

Anyway - I digress. I was talking about the mole, and its eternal usefulness.

One mole of any substance contains 6.02 x 10²³ atoms, molecules or ions (whichever is most appropriate) of that substance. So, one mole of marshmallows contains 6.02 x 10²³ marshmallows; one mole of water contains 6.02 x 10²³ water molecules; one mole of mercury contains 6.02 x 10²³ mercury atoms.

And, one mole of any substance has a mass equal to the relative mass of that substance, expressed in grams. So one mole of oxygen atoms has a mass of 16.0 g; one mole of oxygen molecules (it's a diatomic molecule, see) has a mass of 32.0 g. With me?

The Avogadro hypothesis (named after Amadeo Avogadro, an Italian physicist who died in 1856) asserts that this is true. Actually, it asserts that equal volumes of different gases, at the same temperature and pressure, contain equal numbers of molecules. Which is beautifully simple, and has the far-reaching consequences I mentioned above.

It enables the mass of any given substance to be translated directly into numbers of molecules (or atoms) using the Avogadro constant: the mole.

Thus: the number of moles of a substance is equal to the mass of that substance divided by the molar mass of the substance.

E.g. How many moles are in 52 g of water? Well, the molar mass of water is (2 x 1.01) + 16.0 = 18.02 g mol‾¹

So the number of moles in the water = 52 g divided by 18.02 g mol‾¹ = 2.89 mol (3 significant figures). There are 2.89 moles of water molecules in 52 g of water.

Simples!

And the scariest thing? I'm quite enjoying it all! Next, I shall enthuse about covalent bonds. They are this: aces.

*I can't claim the credit for these analogies. They came from a rather cool chemistry site.