My freezer is set at -21°C (-6°F) and tubs of ice cream come out hard as a rock and are near impossible to scoop. But if I set it a few degrees warmer, yet still way below the freezing point of water, I can scoop it easily. So, is there such a thing as both frozen and *really* frozen? Conversely, a boiling point is a boiling point, I believe. Heating water to a temp above 100°C gets you the same steam that you got at 100, just faster. Right?
In: 102
I think ice cream is more like a paste that has ice crystals in it than a proper solid. The density of things can change at different temperatures but it isn’t that dramatic. If you go crazy with different temperatures and pressures water can form exotic ice types but that isn’t going to happen in your freezer.
Yeah, while water is freezing or boiling, extra energy doesn’t change the temperature but does make the process faster. Once it’s all frozen or boiled off, continued energy transfer will then decrease the temperature (of the ice) or increase the temperature of the steam.
Anyway, icecream is NOT pure water though, so its freezing point isn’t 0 C (32 F), it’s likely lower. Your temperature could be at the freezing point of water, and your icecream would probably be more like yogurt, NOT frozen at all.
An important thing to note about ice cream is that it is full of air. That’s why ice cream needs to be churned when it is made.
Water changes phase at 0C. It’s a liquid above and a solid below. Once it’s a solid, it can actually get much colder. It doesn’t get “solider” tho. The benefit of freezing ice to a much lower temp is that it will remain ice longer bc it will take longer to warm to the phase change temp. Fisherman want the coldest ice they can get bc it will last longer before melting.
As far as heating it goes, at 100C liquid water changes phase to steam. The steam can be heated to much higher than 100C, but liquid water has limited ability to be superheated past 100C. You can do it if you change the pressure.
Edit – more answer
ice cream is typically made by churning the fat sugar water mixture to incorporate air as it freezes. this prevents ice crystals from forming above a certain size. a good ice cream is technically a frozen foam with millions of microscopic ice crystals and should feel like snow even at -21C.
the problem happens when storage is actually not as cold as reported. warmer than -18C, ice crystals can start to fuse into large crystals over time or even over several cycles of taking it out into the room for a few minutes.
same thing happens with snow. if it cycles through warm periods eventually the powder snow becomes rock hard.
Ice absolutely gets harder the colder it gets. Most solids do. That’s why a blacksmith heats the steel before working it.
Your ice cream on the other hand…that getting harder isn’t because the ice is getting harder. Ice cream is a complex mixture of water, fat and sugar. As it gets colder more of the water can freeze and the remaining water has a higher sugar concentration and will need to get even colder to freeze.
There are actually different phases of water ice formed at different temperatures and pressures. Under specific conditions, ice-iii is more dense than water, so it would sink. Being more dense, maybe it’s “harder”, if you could measure it. This is because water molecules arrange in different crystalline structures. But under normal atmospheric conditions in your freezer, ice is ice. And on the stove, boiling is boiling. Pressure is the variable that changes everything.
Interestingly enough, Ice comes in over 17 different forms.
Here’s scishow talking about them:
The phase transitions are distinct. Going from -1c to 1c goes fully from ice to water. You probably already knew that, though.
The exact properties of water, ice, and steam do vary with temperature. Water becomes more viscous at lower temperatures, but it’s never nearly as pronounced as ice cream (which I believe is a colloid?).
Ice actually does get harder as it gets colder. Ice is prone to brittle fracture and will not bend or stretch before it breaks, so it never behaves much like a liquid, but it *does* change hardness.
Steam, of course, changes in density, pressure, and viscosity with temperature.
If youre actually 5 like you claim im not going into pv=mrt. Or transitions/states.
Id say 5 year old. If you put all the water/milk/sourpatch kids in your mouth. Could you put more in there?
If they have donkey brains different story
Otherwise. Its the same then honey. You cant make water boil or freeze more.
Then when its age appropriate explain hydrogen bonds are cool. And other fun stuff.
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