BF2S Forums A question about a glass full of coke with ice

Seal 3 wrote:

It will go down, the ice expands taking up more volmue as it melts less mass will be in the glass

Why do things contract when they freeze then?

Unless my understanding of the physics/chemistry involved is way off the coke should spill out from the glass.

Wouldnt overflow because I would have drunk half of it.

Towelly wrote:

Seal 3 wrote:

It will go down, the ice expands taking up more volmue as it melts less mass will be in the glass

Why do things contract when they freeze then?

Unless my understanding of the physics/chemistry involved is way off the coke should spill out from the glass.

Water is the only substance that I know of that expands when it's frozen. I believe it's unique in that fact.
Yes the level of liquid in the glass would go down.

- Water expands approximately 9% when solified (frozen)source
- A body of ice floats with approximately 10% above the water surface. source

So.. you haven't given us sufficient information.

What % of the ice is floating freely -> 10% above the surface?
How much ice is there altogether in the glass? (under the surface)

DonFck wrote:

- Water expands approximately 9% when solified (frozen)source
- A body of ice floats with approximately 10% above the water surface. source

So.. you haven't given us sufficient information.

What % of the ice is floating freely -> 10% above the surface?
How much ice is there altogether in the glass? (under the surface)

Since this is an American forum, I'll consider this an American glass of coke. Since you yankees drink coke with an absurd amount of ice, let's assume there's plenty of ice below the surface also. And of course there is ice floating at the surface.

Remember though that the glass is nearly spilling, if a drop o coke falls in the glass it will spill over.

I love these questions, I think I am putting some ice to icer now, well not really.

It will stay at the same level.

Coolbeano wrote:

SilentscoutIX wrote:

Water is the only substance that I know of that expands when it's frozen. I believe it's unique in that fact.

Any compound with a bent tetrahedral bond shape will expand when frozen. Anything non-tesselatable, really.

Voosh

That was the sound of your post flying straight over my head.

EVieira wrote:

DonFck wrote:

- Water expands approximately 9% when solified (frozen)source
- A body of ice floats with approximately 10% above the water surface. source

So.. you haven't given us sufficient information.

What % of the ice is floating freely -> 10% above the surface?
How much ice is there altogether in the glass? (under the surface)

Since this is an American forum, I'll consider this an American glass of coke. Since you yankees drink coke with an absurd amount of ice, let's assume there's plenty of ice below the surface also. And of course there is ice floating at the surface.

Remember though that the glass is nearly spilling, if a drop o coke falls in the glass it will spill over.

Hmm.. I like to see this place as an international forum..

Let's say the glass is filled with ice in a way that it barely floats from the bottom of the glass. And that all icecubes are connected together. We could in that case make the assumtion that 10% of the ice is floating above the surface, which also is the edge of the glass. Now, lets go back to the facts we know (also quoted here) about the expanding of water, and calculate.

When the ice melts, it will lose its +9% volume and +10% flotation. And as these are approximate values, we could easily make the assumption that the level of liquid will remain unchanged.

1 unit water, when frozen displaces pretty much its mass when floating in water. Putting aside variables such as mass increase/decrase at temperature changes, we should be able to assume that as the ice melts it will continue to displace it's mass but reduces in volume, until it's completely integrated with the "original liquid". The surface level will remain unchanged.

You will have yourself a flat coke.

Paul Walorski, Part Time Physics Instructor wrote:

The water level remains the same when the ice cube melts.

A floating object displaces an amount of water equal to its own weight. Since water expands when it freezes, one ounce of frozen water has a larger volume than one ounce of liquid water. A completely submerged ice cube weighing one ounce, for example, displaces MORE than one ounce of liquid water. The cube will rise until the volume remaining under the surface displaces only one ounce of water.

If you could remove the ice cube and leave a 'hole' in the water where the cube used to float without disturbing the surrounding water, that hole would take exactly one ounce of liquid water to fill. Let the ice cube melt. Since it is now one ounce of liquid water, putting it back into the 'hole' will exactly fill it and leave the remaining water undisturbed.

Now.. If you were to make a Cuba Libre out of it, the level would fall:

Yasar Safkan, Ph.D. wrote:

However, note that this may not apply to everything. If you had solid alcohol floating in water, when it melts, the level would drop, because water and alcohol mix at the molecular level; i.e. water filling spaces among alcohol molecules.

Source

Last edited by DonFck (2006-12-29 03:28:32)

EVieira wrote:

Lets say you have a glass of coke with plenty of ice. Its filled to the top, just barely not spilling over the top. Once the ice melts, will the coke spill over the top, stay in the same place, or go down?

go down. the hydrogen bonds in Ice cause it to expand as it freezes, and contract as it warms. therefore, the water level will drop, but it will be a negligible amount.

That's it, I'm going to get a soda!

The ice is less dense then the water, as shown by the fact that it floats. This means for the same mass ice takes up more room then water, so when the ice melts it takes up less room.

Water still gets denser as it gets colder, the molecule's of H2O loose energy and move slower and get closer together. But once the water looses enough energy for the H2O molecules to begin to bond together a structure begins to form that makes the water less dense.

Here is water molecules, One oxygen, two hydrogen.

In liquid water each H2O molecule is  free to move around, since there aren't any ridged bonds holding them into position they can move as close to each other as possible

Around 4 degrees Cecilius water starts to form a crystal structure and solidify into ice.
The picture above shows the 2 extra sites on the Oxygen molecule where bonds can form. The dots represent a pair of electrons.
When ice forms each oxygen has 2 hydrogens from other water molecule bond to them.
It forms an orderly structure called a crystal lattice

The structure of the bonds causes gaps and spaces the molecules farther apart then when they where free to fit move freely around each other in  the liquid state.

So water gets less dense as it cools, the expands as it forms an orderly crystal structure, then continues shrinking again as the crystal structure shrinks up with the decrease in temp.

If it is below the ice, the beverage would stay the same, if there is some above the liquid, it will rise and spill.