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Q & A: Freezing Crushed Ice

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Most recent answer: 10/22/2007
Q:
When you freeze crushed ice it all sticks together. Is it possible to stop it sticking?
- Ani (age 12)
Linslade middle, England, Beds
A:
Hi Ani,

You can reduce the sticking by keeping the ice well below the freezing point at all times. The sticking mainly comes from water that has melted on the surface of the crushed ice pieces re-freezing, gluing the ice pieces together. If there never is liquid water present, this process will not happen.

It is may be impossible to keep all liquid water from forming because the process of crushing the ice may melt some water (both due to  and also the fact that crushing the ice adds energy which can melt some of the ice. In addition, if the humidity of the air is high enough, some water will condense on the ice pieces. This last one can be minimized by doing the crushing quickly and in a low-humidity atmosphere.

The low-temperature approach to keeping the ice from sticking is why it is hard to make a snowball that sticks together when it is really really cold outside -- the best snowball-sticking together temperature is right around freezing.

Tom J.

(published on 10/22/2007)

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