What's Going on Here

Anyone want to explain this?  It was sent in one of those emails that sort of go around.

http://1.bp.blogspot.com/-nTsYA2CjxEY/UTHUm65l1TI/AAAAAAAAEvc/99q4byX0znM/s1600/24.jpg
Water straight from the tap becomes cloudy when frozen.
To make ice cubes crystal clear, allow a kettle of boiled water to cool slightly
and use this to fill your ice cube trays.

I know that crystal growth is path dependent.  Is this just the water equivalent of annealing in metal and glass?

Update:  Long-time reader Travis says that boiling the water drives all the trapped air out, making the cubes clear.  Jeez, I so wanted this to be some wonky crystal formation answer

17 Comments

  1. JBK:

    Boiling water, degasses the water--removes dissolved gasses. The degassed water will freeze to a clear ice.

  2. Jim Collins:

    I was watching a "How Its Made" on ice sculptures. They use a vibrating table in the freezer to ensure that the air is removed while the water is freezing to get clear ice.

  3. Sam L.:

    You didn't take Physics in college? Or don't remember it?

  4. Matthew Slyfield:

    A bit tough to do in a standard residential freezer. That would require a commercial walk-in freezer.

  5. marque2:

    My one fridge with an ice maker -when they installed it, they took the water from the hot side of the water heater, which was kind of inefficient, but made the ice clearer.

  6. Matthew Slyfield:

    Yes, but that's closer to the boiling water suggestion than the vibrating table solution. I don't think you could make the vibrating table thing work in a residential freezer.

    "they took the water from the hot side of the water heater, which was kind of inefficient"

    It may actually be more efficient. Hot water can freeze faster than cold water.

    http://math.ucr.edu/home/baez/physics/General/hot_water.html

  7. Mark:

    But how much will this contribute to climate change?

  8. LoneSnark:

    Freezing faster is not the same as being more efficient. That said, as the ice maker doesn't run the water until it gets hot, the water should be room temperature when it enters the freezer. Therefore, the only energy expended was heating the water back in the water heater, then maybe your home a.c. to keep your walls cool.

    Point is, the extra energy expended by tapping the ice maker to the water heater might be too small to measure.

  9. guest:

    As a kid I once put a snowball in a vice in my dad's garage and squeezed it hard enough the snowball became a thin sheet of clear ice, probably for the same reason

  10. marque2:

    You could rent out your back yard to frackers, then the earthquakes would keep your water pure 😛

  11. JBK:

    No, hot water does not freeze faster than cold water. You have to reduce the temperature down to the liquid's freezing point and that means removing X Joules per degree and then remove the latent heat of fusion which is about 33 J per gram for water to get water to freeze.

  12. Matthew Slyfield:

    Did you bother to read the link I provided. The Physics department of the University of California says it can and provides an explanation for why and how.

  13. obloodyhell:

    }}}} Update: Long-time reader Travis says that boiling the water drives all the trapped air out, making the cubes clear. Jeez, I so wanted this to be some wonky crystal formation answer

    Yeah, that's what I thought the answer would be when I first read the question. I suspect you don't need to boil the water, either, just letting it sit for a good while before you freeze it would have a similar effect.

  14. obloodyhell:

    I dunno, there are some pretty powerful battery operated vibrators...
    Those've got to be waterproof... right?

    😀

  15. obloodyhell:

    Feh. Business Majors.... 😀

  16. JBK:

    Probably not, it would just come to equilibrium with the air for whatever temperature was ambient. You can remove dissolved gasses by other means. Bubbling helium thru the water is the preferred method in labs. Using an ultrasonic cleaner will also work but probably not as well. Using a vacuum pump will work too.

  17. Noumenon72:

    Is Travis TJIC? I often wonder what he's been up to, probably holed up in a compound somewhere.