Originally published at: http://www.howtogeek.com/169853/what-if-ice-did-not-float/
Have you ever wondered what it would be like if ice did not float? Perhaps you have never really thought about it, but you might be surprised at the impact such a change would have on our world’s climate. The Periodic Table of Videos channel discusses how ice’s ability to float has a positive effect on our climate in this terrific video.
Lakes and ponds would freeze from the bottom up, which would be disastrous to ecosystems.
Many years ago Isaac Asimov, in one of his science books (as distinct from his science fiction), noted the peculiar property of water that causes it to expand just as it freezes, unlike most other substances which continue to contract as they get colder. As I recall it's related to how the crystals form. This property of water makes life on our planet possible. I've been unable to track down the article even with the help of my friend Google - does anybody recall it?
Ice can form in different ways... the normal way is hexagonal, which is low density, but under extreme pressure scientists have made ice form in other ways, meaning it is denser than water.
The Prof is my old inorganic chemistry supervisor so it's good to see him still carrying on the good work on YouTube!
Not sure about Isaac Asimov's article, but he is absolutely correct. Water is weird, and it's not just the freezing point density change which makes it odd. The whole scenario of hydrogen bonding ensures that water remains a liquid at the temperatures and pressures found on earth. Without the hydrogen bonding, water would evaporate much more quickly than it does now and at higher altitudes on the planet would actually boil, putting much more water vapour into the atmosphere and creating arid zones at altitude. Water also absorbs infrared radiation quite strongly and dissipates it back out at a lower frequency which gives rise to heat entrapment. Basically the extra vapour in the atmosphere would create a greenhouse effect of its own, causing temperatures to rise at the earth's surface, causing more water to evaporate or even boil.
So, without the hydrogen bonding, much of our water could actually be in the atmosphere either as a vapour or as a gas, thus reducing its availability to sustain life.
This very peculiar property of water as well as the bond angle between the two hydrogen atoms (water is V shaped rather than being linear) allow the liquid to form and hence create the correct conditions for life. Without hydrogen bonding, earth would probably not support life.
The reason ice floats is that as the temperature of liquid water drops, just above freezing point (at about 4 degrees C) the slow contraction of size caused by the kinetic energy of the water molecules reducing stops and hydrogen bonding takes over to prevent the water molecules squeezing together any closer so as the temperature drops further, the volume of the ice begins to increase for a fixed mass of water (and subsequently ice) to solid ice floats on warmer water due to the density difference allowing the liquid to provide the necessary buoyancy forces to keep the ice on the surface.
On another note two of the Prof's dreams when I knew him were to drop a cubic metre of potassium into the sea "to see how big the explosion would be" and the other was to create a theoretical substance called "poly water" which in contact with liquid water would initiate polymerisation (taking advantage of hydrogen bonding) to create solid, polymeric water at room temperature. His idea again was to drop it in the sea to see what would happen. Fortunately he never managed to create his polywater sample or we wouldn't be here now!
If ice would sink in water, no life out of water was possible. The entire frozen water would permanently settle on sea-bed, like rock and the water would cover earth.
Thanks again, AA - another fascinating peek at the science of the world around us.
Whiskey on the rocks would be significantly less appealing, that's for sure.
D3343m The essay was in "The Left Hand of the Electron" http://en.wikipedia.org/wiki/The_Left_Hand_of_the_ElectronOne of his "Gentle Readers"
Some easy tests can provide the information to figure it out.
Fill a jar half-full with water and drop in a few ice cubes. Immediately mark the water level on the glass. After the ice melts, check the water level again. Did it rise, stay the same or become lower?
Alternatively, weigh the glass of water containing the ice cubes, and then weigh the glass of water after the ice melts.
Hint: the crystallization of water to ice adds air, allowing the volumetric increase of the frozen water to be light enough to float. The mass of floating chunk of ice is the same as the mass of the water that it contains.
If the Antartic ice shelf breaks away from the land mass of the that continent, world sea levels will rise immediately instead of gradually as the ice melts.
if i did not float james cameron would of never got that oscar because the titanic would of made it.
if ice did not float i mean.
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