Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Making Ice with no air bubbles

  1. Jan 9, 2005 #1
    Is it possible to make very clear ice in a home freezer?

    Tap water ice is often cloudy white, which I think comes from minerals in tap water. Making ice with distilled water is a pretty conclusive experiment, I think.

    However, the ice cubes I make with distilled water still have many small air bubbles frozen into them. I have tried melting and re-using the ice in the hope that there would be less dissolved air in the water on subsequent freezings, but it did not seem to make a difference.

    By examining cubes as they are freezing, you can see that the top gets cooled the most, and this skin of ice can trap air. I have tried putting the water in bit by bit. With a thinner layer of water, I expected the air might reach the top before the water freezes. There are still bubbles.

    I put a container with a small hole in it above a dish. I filled the container and let the water drip out. I cooled the water in the container first, in the hope the drops would freeze rapidly. The hole froze shut before the container could empty, but the ice in the dish below still had air bubbles.
     
  2. jcsd
  3. Jan 9, 2005 #2

    Integral

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Have you tried boiling the water before freezing it?
     
  4. Jan 9, 2005 #3

    cronxeh

    User Avatar
    Gold Member

    Maybe try applying pressure on the closed container of water and freezing it?
     
  5. Jan 9, 2005 #4
    What if you froze the ice cubes under a very inert gas like helium or argon? I'm just guessing here.
     
  6. Jan 10, 2005 #5
    remember, I want to do this in my freezer, so I can't put the water in a closed container with helium.
     
  7. Jan 10, 2005 #6
    try uses a thick and small metal container, freeze the container first and pour warm water in..... the water temperature will drop fast and uniformly..... hopefully this will make a little different........ I will try tis tonight and tell you guys the result....
     
  8. Jan 10, 2005 #7

    rcgldr

    User Avatar
    Homework Helper

  9. Jan 10, 2005 #8

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    The cloudiness is not from minerals, it is from air dissolved in the water. You can get clearer ice, not necessarily perfectly clear, by boiling the water first to drive out the air, then freezing it.

    (Yes, I know it sounds silly to boil water before you freeze but---)
     
  10. Jan 10, 2005 #9

    Q_Goest

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Water is often prepared for experiments where all the air must be removed by exposing the water to a vacuum for a period of time sufficient to get the air out.
     
  11. Jan 10, 2005 #10

    pervect

    User Avatar
    Staff Emeritus
    Science Advisor

    I found this link which confirms Halls of Ivy's statements:

    http://www.engineeringtoolbox.com/24_639.html

    The other thing I can think of to try is to see if you can find or borrow one of those vacuum devices that they sell for freezing food. (I'm not actually sure how well they work though, I just see them advertised all the time on TV, only ninety-nine ninety-nine ninety-nine :-)). But it looks like boiling the water in an open container should work just as well from the solubility chart.
     
  12. Jan 10, 2005 #11

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Boiling the water, just prior to freezing will definitely help reduce air bubbles. You really can not eliminate ALL the bubbles this way, as the water will redissolve air as it cools. You wnat to minimize the time that this water stays liquid, so I would set the thermostat on the freezer to the coldest it can get, and put the freshly boiled water in quickly. If you do certain tests in advance you could optimize the temperature you heat the water to in order to be able to make use of the mpemba effect.

    Since the typical solubility of air in cold water is about 30 cc/L, and an ice-tray holds...what...300 mL or so, that's about 10 cc of air that is dissolved in it. If you can make the total volume of air available to the water of order a couple tens of cc's, then you can slow down the rate of dissolution. So what all this speculation is leading to is that a tight fitting ziplock bag, or something of that nature MIGHT help.

    Final suggestion, and this may not be feasible : there are those vacuum bags that they advertise on TV for putting clothes and stuff into, that attach to a vacuum cleaner or such. Something like that would work like a miracle...I think.
     
    Last edited: Jan 10, 2005
  13. Jan 10, 2005 #12

    Chronos

    User Avatar
    Science Advisor
    Gold Member
    2015 Award

    You can do this with aluminum foil and metal ice trays. Take a piece of foil more than large large enough to cover the ice tray. Form a cylinder about a half inch long in the center of the sheet using the eraser end of a pencil, or similar object. Poke a hole in the top of the cylinder using a round toothpick. Place sheet over filled ice tray [foil cylinder pointing up!]. Seal foil around edges of ice tray. Boil water in tray [set burner on medium, you want a slow boil]. Once boiling and you see steam coming out cylinder hole, remove tray from burner and pinch off cylinder closing the hole [caution, wear oven mit]. This will prevent air from reentering. Freeze to taste.
     
  14. Jan 10, 2005 #13

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Very nice ! :smile:
     
  15. Jan 11, 2005 #14
    This may sound wild but it is proven that Hot Water freezes faster then Cold water. Therefore it wold be more effiecient to use boiled water then freeze it becuase it will have less air and it will freeze faster because it is hot. Since the water will freeze faster it will have less time to allow air to dissolve in it as well.

    Check it out!
    http://math.ucr.edu/home/baez/physics/General/hot_water.html
     
  16. Jan 11, 2005 #15
    I'm not sure if this will work...

    What if you coat the boiled water with a layer of oil, and then freeze it?

    Presumably the oil in the water would stop air being transfered, but if you are using these 'airless icecubes' to consume then I think there is a bit of a health risk :smile:
     
  17. Jan 12, 2005 #16
    No...Remember Boiled water is less dense than oil/ :wink:
    The oil will sink to the bottom of the container/....producing no effect.
     
  18. Jan 23, 2005 #17
    I tried to make a large clear ice cube yesterday, but the result is not satisfactory.

    I used a 20 cm x 30 cm aluminum roasting pan, and put 4 l. of distilled water in it. I covered this pan with aluminum foil, including a vent tube as suggested. This cover, of course, was not air tight. I do not think it could be made so even using a smaller ice tray. I but the pan on my stove and boiled the water. Then I put it into the freezer on top of a tray that had a couple cm thick coating of ice.

    The ice close to the edge, within 5 cm say, is pretty clear, but the center still had a lot of air bubbles and was whitish.

    The air bubbles in the clearer part of the ice have an interesting shape and orientation. They are thin tubes. At the bottom of most of them is a sphere perhaps 2 or 3 times the diameter of the tube. Thus they look a little like a bulb thermometer. I would expect the tubes to be oriented vertically (the air bubble trying to rise out of the ice). Most are at something like a 45 degree angle. Some tubes at the corners are horizontal, and some even go downwards. Why do the bubbles have this shape?

    Some of the tubes reach near the top of the ice. I thought if they did make it all the way to the surface, or near, so that by melting the surface a little the hole would be exposed, I might be able to fill the tubes with water. Then I could refreeze the block and eliminate the hole. Melting the surface with water does not cause the tubes to fill. Assuming the air pressure in a tube is not lower than 1 atm., the air will resist being compressed by a droplet. If the surface tension of the droplet is strong enough it might act like a little beam that gravity is not strong enough to "fracture" and cause to fall. Compare pouring water into a glass (full of air) versus a beam of ice across the top. Is this explanation correct?

    What if I don't want to eat the ice, is there something I can dissolve in it to react with and remove the air?
     
  19. Jan 23, 2005 #18

    Mk

    User Avatar

    Are you sure? I've heard claims that it freezes faster and it doesn't.
     
  20. Jan 23, 2005 #19

    Chronos

    User Avatar
    Science Advisor
    Gold Member
    2015 Award

    Interesting, try leaving the vent open.
     
  21. Jan 23, 2005 #20
    I did not pinch off the opening of the vent after putting it into the freezer. I made a cone of al. foil and poked it up through the covering sheets. The bottom of the cone may have been under the water to start, but I think it fell over because the cone did not freeze into the block.

    Are you the same Chronos on SDMB?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Making Ice with no air bubbles
  1. Air bubbles in pool (Replies: 7)

Loading...