steam

[susanallen45]

why does the volume increase when water is turned to steam

[bernardo]

Liquid water is made up of loads of molecules which are swimming around slowly, bumping into each other and going in all directions. As the water gets hotter, the molecules get more energy and they zoom around faster and faster. Eventually it gets so hot that the molecules at the top of the water zoom off into the air and can no longer be kept in by gravity. When it all evaporates and becomes steam, the molecules are whizzing so fast that they need much more space to zoom around in.

[ianess]

OK.....reasonable answer.

Now let us know how it is that water also expands as it turns to ice and the molecules slow down.

Isn`t physics a wondrous subject?

[bernardo]

The "easy" answer to the second bit is that if water shrunk when it froze (like all other solids) then we wouldn't be here to discuss it because we would not have been able to evolve in the first place.  So it's one of those silly Anthrop ic-Principle circular-argument questions.

 

The proper answer is "I don't know".

 

 

[ianess]

It`s not a circular-argument Bernardo........it is a fact that water is the only substance that I know of that expands on BOTH sides of freezing point and I would just like to know why.

Another one of life`s little mysteries.

[Gef]

When water is cooled it contracts until the temperture reaches 4 degrees Celcius. At that point the molecules have slowed sufficiently that hydrogen bonds can form and these hold the molecules in place and cause them to move further apart as ice crystals are formed.

[ianess]

Gef.........that sounds like a reasonable answer......many thanks.