speed freezing depends, first, on the surface area of heat transfer, and secondly, the thickness of the water layer: the higher it is, the slower will freeze the entire volume of water (andvice versa).Therefore, pour water into the container such that the surface cooling was big enough, and the thickness of the water layer - a little.You can use, for example, the Lednice - plastic substrate for small, shallow containers that produce specifically for this purpose - getting food ice at home.Put a bowl of water in the freezer.Ice is formed much faster than in case if exactly the same amount of water was poured into a plastic cup, for example.
In addition, it is possible to accelerate the fre
ezing of water in the following way.When the temperature is already close to 0, toss in each container odnu- two grains of salt.It would seem a paradox, because we know that salt water freezes at a lower temperature than fresh water.But the paradox is only apparent: the mass of salt will be so insignificant that the water actually remain fresh and grains serve as a kind of crystallization initiators.
If you have a long thin container types of tubes (steel only), you can very quickly get ice with liquid nitrogen.Lower the water tank (with a long clamp or wire) into the dewar, of course, not completely, so that the liquid nitrogen is not filled in it.After some time, remove.Once the vessel wall will heat up the ice can easily be removed.
can be used for quick freezing property of certain chemicals to dissolve, absorb large amounts of heat.For example, there is substance - ammonium nitrate (ammonium nitrate).It is widely used in agriculture as nitrogen fertilizer.If the ice that you want, is not used for food purposes, add ammonium nitrate directly in the tank with cold water and dissolve with stirring.Then he put the container in the freezer.Ice forms in minutes.
when working with liquid nitrogen, observe all safety precautions.When working with ammonium nitrate do not forget that it is a toxic substance.Such ice is in any case can not be used to add to the drink.