WHERE DO THE BUBBLES IN THE ICE COME FROM??

[physics]

i dont know where the thread got moved to so i'll ask the question again...sorryy.

So when u have an ice cube there are these bubbles in there that i have no idea where they come from?

Cause when i pour in the water to be freezed there is no air...i dont think so i was just curious and it would help my curiousity if someone helped.


SORRY IF its a stupid question..

HAPPY NEW YEAR. 2011

[funkyducky]

Impurities in the water, eg. CO2 and O2 molecules that are dissolved in the water.

[Russ]

Two reasons I can think of (ask Mao)

When ice freezes it expands and at a molecular level creates space that didn't previously exist, which can be filled by air from your freezer.

or

The oxygen dissolved in the water comes out of solution as it freezes

[physics]

Two reasons I can think of (ask Mao)

When ice freezes it expands and at a molecular level creates space that didn't previously exist, which can be filled by air from your freezer.

or

The oxygen dissolved in the water comes out of solution as it freezes

:O i get it. thanksss heapss

[ninwa]

i dont know where the thread got moved to so i'll ask the question again...sorryy.

sorry again

[Andiio]

Two reasons I can think of (ask Mao)

When ice freezes it expands and at a molecular level creates space that didn't previously exist, which can be filled by air from your freezer.

or

The oxygen dissolved in the water comes out of solution as it freezes

Agreed, both seem plausible, but not sure which one would be 100% correct. I'm leaning towards the substances found within water though. (Oxygen and so on)

[chrisjb]

I don't know the answer, but i remember that mythbusters did a tihng once where for some reason they needed to have ice without any bubbles. The method used to do this was to vibrate the water whilst freezing it.

[pi]

The opacity of ice formed from water containing dissolved air is due to the presence of bubbles of air in the ice. Both bubble concentration and sizes were found to depend on the rate of freezing. Bulk water saturated with air at 0°C was found to freeze into ice containing about six bubbles per mm3 when freezing proceeded at 0.5 mm min-1 and 300 per mm3 at a rate of 5 mm min-1. Bubbles were formed at the ice-water boundary when the concentration of dissolved air reached a critical value which, for rates of freezing greater than 2 mm min-1, corresponded to a supersaturation ratio of 30. Agitation of the water could prevent the critical concentration from being attained and clear ice then formed.
Other factors which influenced bubble concentrations and sizes were the amount of dissolved air, pressure, thickness of the layer of water ahead of the growing ice and escape of bubbles by buoyancy.

^I think that gives a brief explanation for the bubbles, we need Mao for more

As for making ice without bubbles, try here
The vibrating thing would work because the water needs to be moving (or flowing).

[Mao]

As ice suddenly freeze, multiple crystals grow. (all crystals grow from a small seed). Each of these crystals have only defects at the molecular scale (cannot be detected), and can be considered as solid and pure. Thus any impurities would not grow in the crystal, they get separated out.

As the crystals grow (each a few micron wide), these impurities (oxygen, minerals, etc) coalesce and cannot help but get trapped between crystals, these form the bubbles and needles within the ice.

If you sonicate the freezing solution, these impurities are allowed to coalesce more/escape, thus fewer bubbles/poly crystalline features. Cooling at a slower rate would also work, as even 0 degrees still have kinetic energy and brownian (thermal) motion.

Ice expansion has a small effect