Let’s say I fill three equally-sized containers with tap water.
Container A is placed in a freezer where the temperature is 31F.
Container B is placed in a freezer where the temperature is 0F.
Container C is placed in a freezer where the temperature is -100F.
A few days later I remove all three containers.
Is there going to be any appreciable difference in my three blocks of ice? Will they respond differently when struck with a hammer? Will their size, shape, weight and density all be the same? Will they melt at the same rate?
Let’s say I repeat the expirement with salt water, taken from the ocean. Will the salt water ice behave differently from the tap water ice?
Yes, there will be appreciable differences between the three blocks of ice. Yes they will respond differently when struck by a hammer (stresses will be different due to the different freeze rates). Shape will likely be different. Weight will be the same. Density will be the same at the same temperature. Melt rate will be determined by starting temperature and shape of the ice (given the same environment).
As far as the salt water, the one in the 31F freezer will not freeze. Not sure of the exact freezing point of salt water at various concentrations, but the 0F one may freeze. The -100F definitely will.
It seems to me that the ice that forms in brine leaves the salt behind in the liquid so the remaining liquid would be more salty. Like you I don’t know the freezing point curve for salt solution of various concentrations but there might possibly be a little liquid left even at -100. What we need to know is the freezing point of a staurated solution of brine.
What if they were all first put in a 31F freezer until frozen and then transferred to their respective freezers?
the 0 and -100F ones will probably stick slightly to your hands as they will freeze the surface moisture layer.
I know that for sugar solutions in ice creams, the mixture doesn’t every full set up and typical freezer temperatures. Instead, what happens is that little pockets of concentrated syrup are formed which have a lower freezing point.
Assuming pure water, I don’t think there would be any difference then, other than the normal differences between two solids at different temperatures (density). Why do you ask these questions?
If they are all later brought to the same temperature before testing there would be no noticeable differenece. I expect there would be some difference if you are performing your tests at the temperature of their freezers (I think the colder one would be more brittle, but will have to look it up, this is all informed opinion, not fact).
Ice has about 12 different crystaline forms depending upon the temperature and pressure. At -100F ice could be different physically from ice at 0F. I don’t know if there would be a visual difference.
At the most mundane level, the ice cube in the 31 F freezer would be smaller — the rate of sublimation increases with temperature, and so more of the ice molecules would escape into the atmosphere in the warmer freezers.
Here’s a phase diagram. At normal atmospheric pressure (around 10[sup]5[/sup] Pa), the only forms you’d have to worry about are the hexagonal ice structures Ih & XI. (Cubic ice, it seems, can only be formed via condensation or by raising and lowering the pressure.)
The question is, does it change crystaline forms with change in temperature, or is the form at time of freezing (dependent on freeze rate due to surrounding temperature and het transfer rate) locked until it melts.
Well, if you really want to be a nit-picker, it can be stated that water at -100 °F has slightly less mass than water at 0 °F. But the difference is so small that it would be impossible to measure.
The rate of heat transfer is is greater in proportion to the differences in temp., but slows as the differential narrows. You might be able to notice, w/ the human eye, a difference in the way the -100 ice shatters, but not between the -31 and 0 ice. You would not want to handle the -100 ice and/or it’s container w/ your bare hands. I once worked, as a stationary engineer, in a hospital. Our burn ward had a tissue freezer that went down well past -100. Heavily insulated gloves are a must, to avoid instant frostbite.
Seawater freezes around 28 degrees F, but of course salinity differs in various parts of an ocean and salt seas vary even more.Sea ice does indeed “leave behind” the salt as it freezes.
A few years ago someone was importing glacial ice, from Greenland I think, and selling it to curious wealthy people to serve at cocktail parties, presumable for the popping sounds it makes while thawing in a drink.
It changes structure with temperature at normal pressure into the two forms mentioned by MikeS. To get the others you need to fiddle with the temperature.
There’s nothing unusual about this. Tin changes from a reasonably strong metal to a gray powery stuff at low temperatures. And carbon changes to a highly abrasive form, also at low temperatures.