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Can Melting Ice Overflow a Glass of Water?

Share Your Story: Hot Chemistry Topics


Can Melting Ice Overflow a Glass of Water?

Water expands to form ice. (Thomas Northcut/Getty)

Chemistry Issue or Topic

Hey folks! Years ago I read this book and there was something in the book that bugged me. Months later, while sitting in chem class, I realized the problem. (I was a chem/philosophy double-major until I studied organic, calculus based physics, Kant, and Kuhn--that made me switch to philosophy alone!) I can't remember the title of the book, but there was a short story about a man's death. In the story they tried to say that a man had been having a glass of ice water and the ice had melted and overflowed. NOT condensation, but that the ice had overflowed.

Answer the Question

Assuming regular tap or bottled water is used, it is POSSIBLE to make a glass of water with ice in it, so that when the ice melted the water overflowed? I argue no, because the ice displaces the space that the ice would take up if it were in a liquid state. So the water level would stay the same if nobody disturbed the glass. Any thoughts?

nirjanay answers:

"Its easy. If it was not mentioned that the Ice was fully mergerd inside water, we can assume that some part of it might be above the water level, so when Ice melted the water overflowed"

BIODB8ER responds:

"But since ice takes up more room than the equivalent amount of liquid water doesn't displacement cover that theory?"

marlineller answers:

"water expands when it forms ice. If the ice is floating, it will displace an amount of water that equals the weight of the ice. So even though you have bits of ice floating up higher than the surface of the water, the level of the water will not change in the least bit as the ice melts. However, this presuposes that the ice is floating. For example, you could imagine that you have a 2 foot tall pole of ice, sitting firmly on the bottom of the 6 inch tall glass, with maybe a teaspoon of water around the sides. In that case, displacement has nothing to do with it because you have way more ice in the glass than the glass will eventually hold. So you can have it either way. However in the typical case, few cubes of ice in a glass of water, your intuition is correct, the glass will not overflow. PS. this is a physics question, involving freezing, and water displacement, and not a chemical question involving changing bonds between atoms and molecules. Not that that matters, you have your answer."

Tips and Tricks

  • Normally melting ice will not overflow a glass of water, even if there is ice above the surface of the liquid!

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