Ice and water question:

Water level will fall, probably only filling the glass halfway. Just a guess ; no explanation.

 

Water expands when it freezes, so would contract when melted. The water level would go down. Not too much.

 

level will go down. a few years ago we lost power for about 4 days in February. My family was melting snow on the gas stove so we could flush the toilets (I have a well, so no electricity means no water). a full pan of heavily compressed snow only melted to about 1/2 pan of water.

 

I thought this was a basic third grade science concept.

And you are trying to narrow your selection down to an R8, 458, or 430? Damn I am depressed...

 

Correct.

Water is a very odd compound as it gets bigger in the solid state rather than smaller. I can't remember the physics/chemistry of why.

I don't know of any other compounds that do that, dose anyone?

 

We should be glad it does this, and as a result ice floats. Otherwise lakes would freeze from the bottom up. The layer of ice insulates the remaining water and as a result a body of water of any real depth almost never completely freezes.

It would have been difficult for life to have evolved as it did if a body of water would freeze solid from bottom to top.

BTW, bismuth also has a lower density when solid than in liquid form IIRC.

 

This was on Mr Wizard on Nickelodeon in the 1980s.

When the ice melts, the water will be at the top of the glass. Nothing will spill out.

Why?

Ice is one of the rare compounds that EXPANDS as it freezes. Most compounds shrink. Without this, life as we know it could not exist.

When you look at the situation, the volume of the total ice when it melts will occupy the same volume of the portion that was underwater.

The situation would be different if it were a compound that expanded as it melted....or two different materials.

What is far more interesting about state changes, especially water, it that it takes energy (not just temperature) to change states.

Also, that according to Boyles Law, you can have water as a solid, liquid, and gas at the same time. It is called triple point. You put liquid water under a strong vacuum. This will cause it to evaporate. As you may know, temperature is the measurement of the average kinetic energy / motion

t = 1/2mv2

When there is a vacuum, there are less molecules in the same volume, so the temperature drops. This will eventually lead to freezing.

Looks cool. It is like a piece of ice sitting in boiling water.

[ame]http://www.youtube.com/watch?v=BLRqpJN9zeA&feature=related[/ame]

 

Bismuth.

Wow.

Do I love the depth of knowledge on F-Chat.

 

Unfortunately, as the human female heats up, it also tends to expand.

 

Unfortunate? Splain.

That's a marvel of nature.

 

expand or engorge?

 

Something to do with the properties of hydrogen bonds, if my memory of freshman year chemistry serves. (About a 50% chance of that happening)

 

Sorry for late reply, but ice becomes "bigger" than liquid water (redundancy?) because the hydrogen atoms in water have a bond angle of about 105 degrees and the bond angles of ice between bonded water molecules is wider- 120 degrees.

This happens cuz as water gets colder, it forms a rigid lattice structure, a hexagon, because of the geometry of the bonded H-O atoms, so it creates more space in between them in this hexagon (the 120 deg bonds), where as with water, each single H2O molecule is rather unorganized/random.

This allows water to get "crunched" to fit more compactly. Ice cant do that.

Yup- takes me back to the Reagan years........

 

Guess now you are gonna ask "then why does water have these 105 degree angle bonds"?? Sheesh!

OK, OK- Its cuz the 2 Hydrogens have no choice but to migrate closer together to become 105 deg vs say, a straight 180 degrees apart. In other words, water is NOT H2O (H-H-O), but bonded as H-O-H. Now, Im sure yous all know this basic Chem. Still, its interesting to know why arent the H's straight as a chain (right?).

Its cuz theres another 2 electrons at the other end of the Oxygen . These 2 electrons are "pushing" the 2 H's away from becoming a straight chain (H-O-H). It cant happen! So, (cant draw it here), the H's slide closer together closer to the 105 deg from the straight 180 degree, away from the electrons' force to become closer.

 

When ketchup was a vegetable.

Those were the days.

 

I agree, Tim. Reganomics 101.

(Oh, ketchup also will expand if frozen, as its mostly water.......)

just kidding. dont mean to bust your rear about the science lesson.....

 

correct Water level does not change one bit, when the ice floating on top melts.

All you really need is Archimedes' principle to figure this out. And one thought process to prove it, is to run the experiment "in reverse":

1. Start with a glass of water, filled to some level.
2. Imagine that we isolate a small 3D "section" of water floating at the top.
3. Now imagine that we freeze that "section".
4. Weight of this "section" won't change as we freeze it (freezing a given section mass may change its density & volume, but it won't change its weight).
5. Since the weight of the newly frozen section hasn't changed, the buoyant force required to keep that section floating won't change.
6. Since the buoyant force required to keep the newly frozen section floating hasn't changed, the weight of the (unfrozen) water displaced won't change (this is Archimedes).

Therefore, there is no displacement change in the (unfrozen) water, if we isolate & freeze a small section at the top.

 

Right, Werewolf- buoyancy law. Too bad Archimedes was murdered by the Romans too early- who knows what else he would have discovered.

 

Haven't seen osmosis mentioned yet, so, FWIW - osmosis.

 

Wax, Wax! Youre gonna get a spankin' for not doing last night's 7th grade Biology lesson (pointing right index finger, shaking it parentally)!

osmosis has to do with more bio than chem, of course. Living cells, hypertonic/hypotonic, etc etc etc.........water filtration systems too.