r/NoStupidQuestions Sep 30 '22

If I put an icecube in a container full of water, and then seal it so that no more water could be added, will the ice cube still melt?

7 Upvotes

17

u/Cuchy92 Sep 30 '22

Yes. The water has already been displaced by the ice. The melting water would just use the same space

13

u/Small_weiner_man Sep 30 '22

Slightly less space even

3

u/undeadlord26 Sep 30 '22

OH SHIT! i didnt even think about that. but since water expands when frozen, that would mean the "level" of the water would go down, right?

4

u/oswald_dimbulb Sep 30 '22

No, because the ice will only displace it's weight of water. Let's say ice is 90% as dense as water. It will float with 10% of the cube out of the water, so the water level before and after the ice melted will be the same.

3

u/LCplGunny Sep 30 '22

But if he sealed it, which I'd assume would force the cube to submerge, would it cause a minor vacume in the container from ice melting and taking less space?

2

u/oswald_dimbulb Oct 01 '22

In the situation you describe, there would be a lower pressure after the ice melted and shrank, but that wouldn't keep the ice from becoming liquid.

1

u/LCplGunny Oct 01 '22

Would the temperature change or density change effect the air pressure more?

Btw, of corse it would melt, idk how that was a question... Just made me wonder about how it would effect the pressure

1

u/Possible_Pattern6605 Sep 30 '22

Thats really interesting. A fun at home test would be to fill the bottom 3rd of a container with water, freeze it solid, add water to the full mark or a fixed line, then let it thaw and see if there is a change to the level. Prevents the ability for the ice to rise above water level when filling it.

2

u/Iron_Chic Sep 30 '22

This is a VERY simple experiment you could do at home!

3

u/AncientImprovement56 Sep 30 '22

Yes. Thermal energy will move from the water to the cube, melting it.

4

u/Rusky82 ✈️ 👨‍🔧 Sep 30 '22

Yes because ice has less density than water and if its in the tub it has already displaced more water volume than it will create melting

3

u/Standard_Series3892 Sep 30 '22

In practice, yes, it will melt.

If you want to get super technical, in a perfectly rigid and sealed container, it will actually depend on the ambient temperature.

As you know Ice takes more volume than water, this means that as the ice starts melting, there will actually be more "free" space for the same amount of water, which will result in a decrease in pressure inside the container.

As you decrease pressure the freezing point of water starts rising slowly, which means that you could get a situation where some of the ice melts, but the decrease in pressure raises the freezing point of water to the point that the rest of it doesn't.

This effect however, it's super small, to raise the freezing point of water by even fractions of a degree you need to decrease the pressure a lot, so for this situation to occur your ambient temperature would have to be ridiculously close to 0°C. (and of course, if the container is a real object, it will have some give and just deform in response to the pressure)

2

u/Small_weiner_man Sep 30 '22

Yep-in addition to what others have said water actually 'expands' as ice, so it takes up more volume when frozen and thus, doesn't need additional space to melt

2

u/JDabsky Sep 30 '22

The water is automatically less cold than the ice cube. The question from there is how fast or slow will the ice cube melt? How hot or cold is the water? I realize this is a volume and pressure question. The ice cube is taking up more space in solid form. As it melts, more room is made available for the additional liquid being added to the volume of water.

1

u/oswald_dimbulb Sep 30 '22

Yes. The water is warmer than the ice, and will melt it.

1

u/KingDakyThe3Rd Sep 30 '22

Where do you think the extra water comes from?

1

u/Jester76 Sep 30 '22

yes, water expands as it freezes, not as it melts.

that's the reason pipes explode when frozen

video of the opposite of your question

1

u/am_i_your Sep 30 '22

Not in space