Why ice Cubes float

[Goosemaster]

The answer is very simple...because of a change in densities...

What is perplexing is how perfect it really is...heat rising in a drink will be countered with the ice waiting for it above.....doesn't it seem just too perfect? Their critical points(ice and water) are just too convenient compared to other substances.


Hopefully someone will understand what the hell I am trying to say.

 

[Shalmanese]

You mean that if Ice were not the way it is, life could not have happened?

 

[Shalmanese]

and BTW: I was just looking at the side ad panel with the funky context thing and I noticed they were trying to sell me "ice melt". wtf is ice melt?

 

[Mday]

water is has the highest density at 4 C, which is a liquid. and the H2O molecule causes strange behaviors which make water somewhat special.

 

[Spacehead]

Originally posted by: Shalmanese
and BTW: I was just looking at the side ad panel with the funky context thing and I noticed they were trying to sell me "ice melt". wtf is ice melt?

No snow or ice where you live? It's for melting the ice off of sidwalks & such.

 

[RossGr]

It could be said that life exists because of this strange behavior of water. If ice sank lakes and rivers would freeze from the bottom up, not nearly as hospitable for life as the layer on top of the water.

 

[wviperw]

What is perplexing is how perfect it really is...heat rising in a drink will be countered with the ice waiting for it above.....doesn't it seem just too perfect?

You mean that if Ice were not the way it is, life could not have happened?

Something happened to me the other day that I'll never forget. I was driving to work like I normally do, and of all things, I saw a licence plate that read "RFG 197!" I mean, what are the chances that I'd happen upon that very licence plate at that very time!

 

[hatboy]

Just in case anybody's curious, the reason that ice has a lower density than liquid water is because of what are called hydrogen bonds. A hydrogen bond is a type of dispersion force that exists between hydrogen atoms and electrons on other molecules. In ice, hydrogen bonds form between the hydrogen atoms on some water molecules and the oxygen atoms on others. Interestingly, these bonds hold individual water molecules farther away from each other than they would be on average when water is in the liquid state and all of the molecules are bouncing around randomly. Hence, ice has lower density.

I knew I took Chemistry in college for a reason.

 

[AEB]

Water is a very unique substance, one of my biology teachers in High school knew almost everything there was about water, he once spent an entire lecture explaining hoe ice melts off a pond, its interesting stuff.

And about the ice melt: i live in Alaska and if its similar to what they have here it lowers the freezing point of water so , the ice melts, its kinda like "super cooling". you can try this at home. put two cups filled with water in the freezer, only put salt in one and see what happens!

 

[Krutoy]

Originally posted by: hatboy
Just in case anybody's curious, the reason that ice has a lower density than liquid water is because of what are called hydrogen bonds. A hydrogen bond is a type of dispersion force that exists between hydrogen atoms and electrons on other molecules. In ice, hydrogen bonds form between the hydrogen atoms on some water molecules and the oxygen atoms on others. Interestingly, these bonds hold individual water molecules farther away from each other than they would be on average when water is in the liquid state and all of the molecules are bouncing around randomly. Hence, ice has lower density.

I knew I took Chemistry in college for a reason.

Props

 

[zephyrprime]

the reason that ice has a lower density than liquid water is because of what are called hydrogen bonds

I disagree with you about the hydrogen bonds thing. Hydrogen bonds are what keep water liquid at room temperature rather than a gas. In ice, water molecules are bonded by hydrogen-oxygen covalent bonds - not hydrogen bonds.

What makes ice less dense than water is that ice is crystaline and it's structure is sorta a 3d hexagon. These hexagons have a little hollow space in them and that's what makes ice less dense.

 

[Shalmanese]

Ice is hexagonal BECAUSE of the hydrogen bonds. With liquid water, the hydrogen bonds are too weak and all it does is makes water slightly mroe viscous (Which is why water has such a high surface tension). However, if you SLOWLY cool the water, the molecules form a regular crystal due to the hydrogen bonds. There is a form of ice called amourphous (sp?) ice which is caused by rapidly freezing water. Its actually more dense and has no structure.

 

[Lynx516]

I have a brillient book at home about water and there are infact 14 different states it can form into. Water forms into hexagons like Shalmanese said because of hydrogen. The state he si talking about which is dencer infact does have a structure and it is where the hexgons overlap therefore filling the space more easily.

 

[Shalmanese]

No, the state I was talking about by definition has no structure because you cool it so fast the molecules dont have time to form a structure. Maybe your thinking of one of the other 13 structures . As a side note, glass is also formed by rapid cooling. If you slowly cool glass, it actually becomes opaque IIRC.

 

[mooncancook]

hmm... there must be an ultimate Creator of everything. these kinds of things can't be out of random

 

[mechBgon]

Originally posted by: Lynx516
I have a brillient book at home about water and there are infact 14 different states it can form into. Water forms into hexagons like Shalmanese said because of hydrogen. The state he si talking about which is dencer infact does have a structure and it is where the hexgons overlap therefore filling the space more easily.

Yeah, I vaguely remember some fascinating charts from my ChemE textbooks showing the various states of water at various pressures and temperatures. Hey, I found one: Ice at upwards of 800°F/400C? Sure, why not!

 

[BoberFett]

Wow, and I thought I was strange when I pondered the properties of water. I've sometimes wondered why water was a unique substance, whereon freezing it expands rather than contracts like most other substances.

I guess that isn't such a strange thing to wonder about after all.

 

[Smilin]

Related question...

This is one of those things that 'some kid' swore the teacher proved to them in high school but I've never been able to swallow it:

An ice cube tray of warm water will freeze faster than a tray of cold water.

The explanation revolves around the fact that the warm water has convection currents and tends to cool uniformly whereas the cold water will freeze quickly on the top layer and then more slowly for the rest. If someone can help 'this kid' out and prove this to me I'll be grateful...it's always seemed a fascinating idea.

The reason I don't by it:
The warm water will *become* the cold water and the convection will have stopped by that time...and then you have an even race between the two except the cold water has had a head start while the warm was cooling.

 

[sgtroyer]

I think the answer to this one is, it depends. Or, it's complicated.

Try this link from the physics faq

Your interpretation, that hot water will become cold water, was my first kneejerk reaction, too. But water can be described by more than just one variable. So by the time the hot water becomes cold there are other properties about it that make it freeze faster, under some special conditions. Check out the link, it's good.

 

[f95toli]

I know a guy who does(well, did) research on surface properties of metals using spectroscopy. The samples are placed in a high-vacuum chamber which is cryopumped, which means that it is really cold, around 80 K, and you can also vary the temperature of the walls in the chamber.
A couple of years ago he and some of his colleagues decided to play around a bit with their equpment so they did the following experiment: Once the chamber had been pumped down they let some water vapours in, a tiny amount, just enough to cover a cold surface with a few atomic layers of ice. Once the ice has formed they varied the temperature while doing spectroscopy (basically by looking at refelcted laser-light).
It turned out there are many different phases, possible structures and I don't know what. Ice is extremely complex and I don't think they were really aware of that when started, Two years have passed and they are still looking at ice and most of their research is now focused on this material, it is actually a very active field of research.

This is just another example of why it is important to play

 

[Shalmanese]

Originally posted by: mooncancook
hmm... there must be an ultimate Creator of everything. these kinds of things can't be out of random

Think of it this way, if Ice didn't have that property, then there wouldnt be sentient beings around wondering how amazing ice was. Theres no requirement of a absolute being.

 

[Pudgygiant]

Originally posted by: wviperw

What is perplexing is how perfect it really is...heat rising in a drink will be countered with the ice waiting for it above.....doesn't it seem just too perfect?

You mean that if Ice were not the way it is, life could not have happened?

Something happened to me the other day that I'll never forget. I was driving to work like I normally do, and of all things, I saw a licence plate that read "RFG 197!" I mean, what are the chances that I'd happen upon that very licence plate at that very time!

I'm probably the only one that missed what "RFG 197!" means. Someone enlighten me please.

 

[Barnaby W. Füi]

Originally posted by: Smilin
Related question...

This is one of those things that 'some kid' swore the teacher proved to them in high school but I've never been able to swallow it:

An ice cube tray of warm water will freeze faster than a tray of cold water.

The explanation revolves around the fact that the warm water has convection currents and tends to cool uniformly whereas the cold water will freeze quickly on the top layer and then more slowly for the rest. If someone can help 'this kid' out and prove this to me I'll be grateful...it's always seemed a fascinating idea.

The reason I don't by it:
The warm water will *become* the cold water and the convection will have stopped by that time...and then you have an even race between the two except the cold water has had a head start while the warm was cooling.

Back when I was flippin' burgers at McDonalds for a living, this guy (who is stupid, btw) said that a thermos tank (the ones they put juice in and loan out) full of hot water would freeze faster than one with cold water, based on the common knowledge that hot water thrown in the air in winter will vaporize, while cold water won't. Anyways, I proved the jackass wrong, we filled them up and stuck them in the freezer, lo and behold the warm one stayed warmer the whole time.

Anyways I just felt like sharing that story, I'm not sure why hot water vaporizes in winter air, but I do know that little tiny bits of water flying through the winter air are very different from larger amounts of water sitting in a container in a freezer.

 

[Hayabusa Rider]

Originally posted by: Smilin
Related question...

This is one of those things that 'some kid' swore the teacher proved to them in high school but I've never been able to swallow it:

An ice cube tray of warm water will freeze faster than a tray of cold water.

The explanation revolves around the fact that the warm water has convection currents and tends to cool uniformly whereas the cold water will freeze quickly on the top layer and then more slowly for the rest. If someone can help 'this kid' out and prove this to me I'll be grateful...it's always seemed a fascinating idea.

The reason I don't by it:
The warm water will *become* the cold water and the convection will have stopped by that time...and then you have an even race between the two except the cold water has had a head start while the warm was cooling.

Good you didn't buy it. Should be in Snopes. It isn't true.

 

[f95toli]

It is true, but the conditions have to be just perfect. Try the link to physics faq above, they explain the process quite well. There have been a few articles in for example Scientific American about this.