Neil deGrasse Tyson Explains Why Ice Floats
StarTalk・2 minutes read
Ice floats due to water molecules expanding when frozen, making ice less dense than liquid water, and only 10% of an ice cube is above the water level. Arctic ice melting won't raise sea levels, with the main concern being land ice melting, and applying pressure delays ice freezing but poses a risk of pipe breakage.
Insights
- Ice floats due to water molecules expanding when freezing, making ice less dense than liquid water.
- Applying pressure to ice can delay freezing and create ice spheres by melting the ice into a ball shape that freezes instantly when the pressure is relieved.
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Recent questions
Why does ice float on water?
Ice floats on water because when water freezes, the water molecules expand by about 10%, making ice less dense than liquid water. This unique property allows ice to stay on the surface of water bodies, insulating the water beneath and protecting aquatic life during winter.
What happens to broken pipes when ice thaws?
When pipes break due to frozen water inside, they do not leak immediately. Leakage occurs when the ice thaws and moves out of the way, creating space for the water to escape. This delayed leakage can lead to water damage in buildings.
How are ice spheres for drinks made?
Ice spheres for drinks are made by pressing ice under pressure, causing it to melt into a ball shape. Once the pressure is relieved, the water refreezes into a solid sphere. This method creates a visually appealing and slow-melting ice sphere for beverages.
Can ice freezing be delayed by applying pressure?
Yes, ice freezing can be delayed by applying pressure, as seen in the process of making ice spheres. However, applying pressure to ice can be risky, as the expansion of ice when freezing can lead to pipe breakage. It is essential to handle ice carefully when applying pressure to avoid damage.
Why doesn't melting Arctic ice raise sea levels?
Melting Arctic ice sheets floating on water do not raise sea levels significantly because they are already displacing their weight in water. The main concern for rising sea levels is the melting of land ice, such as glaciers and ice caps, which can contribute to the increase in ocean levels.
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Summary
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Ice: Density, Expansion, and Insulation
- Ice floats because when water freezes, the water molecule expands by about 10%, causing ice to be less dense than liquid water.
- In a glass of water with an ice cube, 10% of the ice cube will be above the water level, while 90% will be below.
- Arctic ice sheets floating on water won't raise sea levels when melted; the concern is land ice melting into the oceans.
- Ice freezes at 32 degrees Fahrenheit but can be delayed by applying pressure, risking pipe breakage if the ice expands.
- Broken pipes don't leak immediately; leakage occurs when the ice thaws and moves out of the way.
- Cooling water makes it denser until it reaches 3 degrees Celsius, where it's at its densest before freezing.
- Ice floating on top of water insulates the water beneath, protecting aquatic life during winter.
- Ice skating is possible because applying pressure to ice melts it into water, allowing for smooth gliding.
- Ice spheres for drinks are made by pressing ice under pressure, causing it to melt into a ball shape that freezes instantly when the pressure is relieved.
