So I fill up an ice cube tray with water all the way to the top. I put them into the freezer. Several days later I come back and of course the water is frozen, but the water level is now half what it was when I put it into the freezer. Several days after that, the ice is all but gone.
I don’t think evaporation could be used to explain this, so by what means is the water escaping, and where is it going in an airtight, freezing environment?
Check for holes in your ice cube tray?
Try doing it again… experimentation is always the best way 8)
It isn’t holes, as the level continues to drop, even after the water has solidified into ice.
Also, this happens everytime I make ice
obviously it is probably something with my freezer, as not everyone experiences this phenomenom, but what about my freezer is causing this? coolant leak? Ice bandits? alien technology?
Why not? Evaporation is indeed important on (almost) all interfaces, and there will be considerable evaporation from the surface of the icecubes, untill the air is saturated. (Although the air quickly gets saturated at low temperature.)
This water vapour can then condense again, especially if you have any area colder than others, such as the cooling elements.
The only thing I don’t understand is your comment about ‘airtight enironment’, what do you mean with that?
well when you close a refrigerator (sp?) or freezer door, it creates an airtight seal for the compartment withing. This is why you are warned as a kid not to play in old refrigerators (for those of us that grew up watching this, it was displayed in the sit-com “Punky Brewster” with the oh-so hot Soleil Moon Frye). Once the door is shut it is an airtight enVironment (sorry for the mispelling in my earlier post)
Freezers are designed to have very dry air. The moisture is taken out via condensation somewhere in the mechanism. This is what keeps your freezer from frosting over.
In the old days, freezers would fill up with frost. Every time you open it, you let more warm, moist air in, which then condenses and freezes. (Cold air can’t hold as much moisture, e.g., low humidity in winter.) you occasionally had to de-frost them: unplug/turn-off the freezer, leave the door open and let the frost melt and evaporate. It was a good idea to place a fan in front of it.
Ice is always exchanging water molecules with the air, just like liquid water is. A few molecules pop off, a few from the air get trapped. If the air is dry enough, the net result is the ice loses more than it gains. I don’t know if the term evaporation strictly applies to ice, but it is the same process.
I thought going from a solid to a gas was sublimation, not evaporation.
Telemark is indeed correct. What is happening is called sublimation.
Sublimation is a special case of evaporation. So, yes, you’re correct.
so if i put a large amount of ice in there, let it stay in for a while (say 24 hours) then put in another tray, would the new tray still loose moisture? is there a way to measure what point would be the cutoff to where the air has sufficient water molucules to stop sublimation?
The ice will stop sublimating when the vapor pressure of airborn water equals the vapor pressure of the sublimating ice. When that happens depends on the temperature.
Mega Dave, the same thin happens to me when I leave unused ice in the freezer for a long time. It’s not at all unusual.
As long as you are using a frost-free freezer you will still lose your ice cubes, unless you seal them in an airtight package.
I learned this as a kid. We used to make super snowballs in winter and store them in the freezer, planning on a snowball fight in July. Of course, those big snowballs had turned to tiny ice balls. Sublimation killed them.
That’s why, as I tried explaining to my wife, we have to eat all the ice cream within a few days. If you leave it in longer, it sort of dries out and gets all sticky and yucky.
Yes, assuming we reach a steady-state.
It is perfectly possible that the air never becomes saturated though, if there are cold spots somewhere else, where the water vapour can condense/sublimate. In that case, there will be a net transfer of water from the (warmer) ice to the (colder) cooling elements, that will go on as long as there is a temperature gradient - or most likely until there’s no ice left.
This process is rather slow though.