Why do icecubes float in water?

Whaaaa? If the ice caps melted there would be a lot more water in the oceans, so the water level would presumably rise.

 

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very true. I was wrong

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thanks

 

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Then why is water most dense at 3.96 degrees celsius?

Not quite true. Water has a very high surface tension, due to none other than hydrogen bonding (most of water's anomalies are due to this). This certainly does help things to float on it's surface.

That is very interesting about the polar ice caps, and the water level dropping.

 

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Hydrogen bonding decreases the density of water and is most influential at low temperatures. Simple thermal expansion also decreases the density of water and is most effective at high temperatures. Hot water will decrease in volume as it cools, just like most other materials. Below 4 degrees Celsius the average kinetic energy of the molecules becomes so low that hydrogen boding begins to order the molecules into a lattice, which increase the volume. 4 degrees is as cool as you can get water without extensive lattices forming, so that's where water will have the highest density; any cooler and the decrease in volume from thermal contraction will be canceled out by the effects of H bonding.

It is true that H bonding can prevent very light things like insects from sinking, but it isn't really buoyancy. The hydrogen bonding that occurs along the surface of the water forms a semi-solid elastic layer that supports the weight of small objects. It isn't floating any more than a book is 'floating' while sitting on my table. It's simply resting on a surface.

 

Why sciforums rocks:

It's conversations like these that make it all worth while eh? Take a simple question like the title of this thread and booya baby, we're laying it down all scientific like. You guys kick ass. Love live brains!

LOL

 

Thanks for taking the time to explain it to my non-chemist self Nasor. It turns out that the water strider was the exact case I was thinking of when I mentioned surface tension.

 

You're welcome. I think water is very interesting. Of course I'm also a gigantic nerd.

 

Nasor ...

Actually, 'water does float in water' due to different salinity (density)
and temperature (thermoclines). Best example is the Gulf Stream.

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