06-18-2013, 02:52 PM
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Molecules do not change in surface area. When talking about a liquid they can only change in volume and density the molecule is what it is. It is H2O the molecule can not change in surface area unless it stops being H2O. You are correct that cooler water molecules are moving slower. Temperature effects the activity of the molecules. When liquid or gas molecules are all bouncing around and colliding with each other having a good time, this is do to temperature effecting their energy. The more they bounce/faster they are moving the more they hit other molecules and the more those bounce. The result is they occupy more space. Lost of energy equals a loss of temperature equals less movement and water becomes more dense as more molecules can occupy the same space as before. Dry ice(solid CO2) is cold as $#!! because it has to be, it can not be that dense or take a solid form unless it has little energy. When Co2 dissolves in water there is interactive hydrogen bonding with the H2O molecules. The more bonds formed with H2O molecules around it the happier and more stable things are. The less bouncing around the more interactions H2O will have with CO2 and the higher the solubility. I'm still not entirely sure if that is completely correct or the only way temperature effects solubility.
They are infamous be cause they literally are infamous. The BBC and NGC both have documentaries on them if you are interested one is on youtube under 'killer lakes'. In the 80's Lake Nyos caused the sudden death of 1,700 people living in the lake basin and about twice as many livestock. This was due to a massive and violent release of CO2. Nyos is almost 700 feet deep, as mentioned previously colder the water and higher the pressure(deeper) the more CO2 water can hold. When a large disturbance occurs in water that is heavily saturated it can cause the gas to come out of solution in a chain reaction. The bubbles draw water up, suddenly CO2 rich water is being pulled towards less pressure and more CO2 is gassing out and more bubbles and so on and so on. This continues rapidly until the lake suddenly turns-overs with its lower layers coming to the surface and mixing with other layers which is not good nor normal and results in releasing much of the trapped CO2. CO2 being heavier then air the cloud of CO2 displaced all the oxygen around the lake leading to suffocation. These lakes are unique in this aspect and the only example I know of where excessive CO2 input occurs in nature.