## Today’s Science Lesson

December 17, 2008

Can you make ice cubes faster if you start with hot water? No. The rate at which the temperature changes is related to the difference in temperature.  Therefore, hot water will cool faster at first than cool water, but the temperature will never drop below the temperature of the cool water.  For example, let’s say that in the first five minutes, the temperature drops from 90C to 80C for the hot water and from 25C to 23C for the cool water.  By the time the hot water gets down to 25C, the cool water will be down to maybe 12C.  It can never catch up.  If you have two identical thermometers, you can try an experiment with two containers of water, but you need to set each of them on a thin piece of wood or several sheets of paper and not directly on a shelf coated with ice.

Why does water evaporate on the surface? The average energy of molecules is simply a function of the average temperature of the material.  However, molecules are in constant motion, even in a solid.  In water, some of the molecules have higher energy than the average, which means a higher velocity.  If a molecule with higher energy happens to be going toward the surface from within the liquid, it may have enough energy to escape the surface.  A measure of this is the vapor pressure of the liquid.  As I mentioned, even H2O molecules can even escape from the surface of ice.  That’s called sublination.  You asked how the molecules can then stay in the air.  Water molecules are actually lighter than air molecules.  Molecular weight 18 as compared to 28 for nitrogen and 32 for oxygen.

Whaa??? All I know is that the water looks like a hot steaming cup of STHU.

The water in the bay looks like it is steaming right now.

If you read or saw “The Mist” by Steven King this looks downright spooky.

## Just Another Day on the Bay – Beautiful South Padre Island

October 11, 2008

Can you see the moon in the sky?

Just looking at the picture above gives you an idea of how picturesque it is in the South Padre Island area of South Texas. This was taken even before I went out on the bay.

Big sailboat.

This boat’s sheer size caught my attention.

I envied this kayaker because but it is something I have always wanted to do. It must be awesome being able to be on the water like that and powering yourself across such a wide expanse of water. It must feel awesome!

Even concrete can look cool sometimes.

Headed out to the bay for some fishing.

Can you see the teeth on this guy? These take skill to catch.