Science for Kids/freezing water in different containers
Bob P wrote at 2015-07-28 15:00:25
If the container has oblique sides, then expansion of the ice will tend to result in an upward force, which will be less likely to break the container. Imagine a container that is a nice rectangular prism: all the sides are perpendicular to each other. If the ice expands in all directions as it freezes, it will push against the parallel sides, putting force on the container. If the container is, say, conical or pyramidal, then the force to the sides will just tend to push the ice up out of the container slightly.
I'm more concerned by the answer that says water expands as it freezes due to degassing. While that might add to the expansion - obviously ice with trapped air will be less dense than ice without - that is a misleading explanation. Even without any dissolved air, water will expand as it freezes. This is due to the organization of the water molecules when they're free to move around, compared to the organization they adopt in an ice crystal. This is not a common property of materials: most materials are denser in their solid form than their liquid.
Glacial ice will not sink. If it did, all the glaciers would be at the bottom of the ocean. It has nothing to do with bubbles.