Have you ever made ice in your freezer and found ice spike have formed? Here is how to make them delibratly:
To see your own ice spikes, make ice cubes in an ordinary ice cube tray, in an ordinary household freezer, but using distilled water, which you can buy in most supermarkets for about a dollar a gallon. We’ve tried several different freezers, and almost always got some ice spikes to grow.
How do ice spikes form?
Ice spikes grow as the water in an ice cube tray turns to ice. The water first freezes on the top surface, around the edges of what will become the ice cube. The ice slowly freezes in from the edges, until just a small hole is left unfrozen in the surface. At the same time, while the surface is freezing, more ice starts to form around the sides of the cube. Since ice expands as it freezes, the ice freezing below the surface starts to push water up through the hole in the surface ice (see diagram).
If the conditions are just right, then water will be forced out of the hole in the ice and it will freeze into an ice spike, a bit like lava pouring out of a hole in the ground to makes a volcano. But water does not flow down the sides of a thin spike, so in that way it is different from a volcano. Rather, the water freezes around the rim of the tube, and thus adds to its length. The spike can continue growing taller until all the water freezes, cutting off the supply, or until the tube freezes shut.
Why distilled water?
Most ice cube trays produce a few spikes, but usually only if distilled water is used. Millions of people make ice cubes every day using ordinary tap water, and most don’t see ice spikes. Oddly enough, some people often get plenty of ice spikes using ordinary tap water, but this appears to be rare.I have some ideas about why distilled water might make ice spikes more readily than tap water, but so far I cannot explain why some tap waters make copious ice spikes. We measured the probability of ice spike formation as a function of salt (NaCl) concentration in distilled water, at a fixed temperature of -7C, which is shown in the graph at right. Very little salt is needed to kill the ice spikes. All tap waters contain relatively high concentrations of various mineral salts, so apparently different impurities have different effects on ice spike formation.
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