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Q & A: Volume of Water after Freezing

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Most recent answer: 02/16/2020
Q:
what is the % increase in volume when water changes from liquid to solid
- patrick struzynski (age 45)
East Aurora,n.y. USA
A:
Dear Patrick,

The answer to your question is that, in general, a given volume of liquid water at room temperature will increase in volume by about 9.05% after freezing. Most materials do the opposite, that is, the solid form of most substances is more dense than their liquid form.


( University of Toronto)
[Above] Before freezing, liquid water molecules are somewhat free to move around.


( University of Wisconsin--Green Bay)
[Above] When frozen, water molecules form crystal structures. This is the most common form of crystallized H2O, called "Ih". The "h" in Ih is from it's "hexagonal" structure which may or may not be easy to see here. It is less dense than the liquid form of water above since this crystal structure takes up more volume than the free-to-move-around liquid water molecules. (You can ignore the different colors--each ball represents a full water molecule.)


Interesting note: Ih is not the only form of crystallized water. If the water is put in a high pressure environment, frozen quickly or put in extremely low temperatures, frozen water will have other crystal structures which are more dense than liquid water. There are about 15 kinds of ice crystal structures, but Ih is the most commonly found crystal structure on Earth.

Hope that helps answer your question!

Sincerely,
John

(published on 03/12/2011)

Follow-Up #1: Melting ice and sea levels

Q:
I am sure I am being obtuse, but would you indulge my curiosity? Given that 1.7 % of the Earth's water is locked in ice, presuming much of that ice is below sea level, and that ice when it melts has 9-10% less volume; why do scientists assert that the melting ice will raise sea levels?
- Daniel (age 60)
Ridgecrest, CA, U.S.A.
A:

You are right, if a floating iceberg melts there will be no effect on the sea level.

However, most of the ice is in the glaciers and snowpacks of the Antarctic and Greenland. When they melt the sea level will rise.

LeeH


(published on 06/13/2017)

Follow-Up #2: melting ice and sea level

Q:
What about all the ice that is in the water? A large portion of ice in the antarctic and all the ice on the north pole is in the water and if this melted one would think the water level would drop. KR
- Knute Reine (age 80)
Bonogin
A:

The floating part of the ice is about 9% above water, precisely because ice is less dense than water. So when floating ice melts, there is approximately zero effect on the water level. As Lee wrote, the large areas  of ice that are on land are raising sea level as they melt.

It's easy to do this experiment at home, with some ice cubes floating in a glass of water. See if the water level changes as they melt.

Mike W.


(published on 02/16/2020)

Follow-up on this answer.