Ice Cubes Clump
Most recent answer: 10/22/2007
Q:
In my house refrigerator I have found that, ice cubes in the Ice Bucket gets clumped together. How does this phenomenon take place? Does the atmospheric temperature play a role in this?
Thanks and Regards
Rajesh...
- Rajesh Swarnkar
India
- Rajesh Swarnkar
India
A:
I can explain why there’s a tendency for the cubes to clump, but I’ll have to guess a little about exactly how it happens.
In thermal equilibrium, things tend toward a state of lowest ’free energy’. Ultimately, that’s because such a state is can be constructed with a larger number of quantum states of the the system and its environment, and nature seems to shake things up so that any allowed quantum state is equally likely.
For ice, the molecules at the surface have higher free energy than those in the middle. largely, that’s because they are missing some of the bonds that the middle molecules have. So left to itself for a very long time, ice tends to form lumps with low surface area. In the case of ice cubes resting on each other, there is also an increase of free energy at the points where the cubes are in contact and the pressure squeezes the ice. Melting those contact points so the cubes fit together better without high-pressure spots reduces the free energy. Pressure tends to melt ice, because liquid water has a lower volume.
Apparently a thin layer of molecules at the surface can melt, migrating out away from the contact points. Farther out, where the pressure is lower and the the water can freeze between the cubes with very little surface area, it refreezes.
In addition, if there is enough moisture in the atmosphere and the cubes are cold enough, some water can freze right out of the atmosphere, filling in the gaps between the cubes.
What I’m not at all sure of is the relative importance of the pressure effect and the simple reduction of surface area effect. Also, I’m not sure how about the relative imporatnce of the vapor and of the surface liquid in moving molecules around.
Mike W.
You can check the hypothesis that moisture from the air is condensing on your ice cubes and then freezing by looking for fuzzy frost on your ice cubes. Another idea of what could be going on is that your ice cubes are melting a bit and then re-freezing if the temperature in your ice bucket goes through cycles of warming and cooling. This will certainly speed up the process of clumping ice cubes together.
Tom
In thermal equilibrium, things tend toward a state of lowest ’free energy’. Ultimately, that’s because such a state is can be constructed with a larger number of quantum states of the the system and its environment, and nature seems to shake things up so that any allowed quantum state is equally likely.
For ice, the molecules at the surface have higher free energy than those in the middle. largely, that’s because they are missing some of the bonds that the middle molecules have. So left to itself for a very long time, ice tends to form lumps with low surface area. In the case of ice cubes resting on each other, there is also an increase of free energy at the points where the cubes are in contact and the pressure squeezes the ice. Melting those contact points so the cubes fit together better without high-pressure spots reduces the free energy. Pressure tends to melt ice, because liquid water has a lower volume.
Apparently a thin layer of molecules at the surface can melt, migrating out away from the contact points. Farther out, where the pressure is lower and the the water can freeze between the cubes with very little surface area, it refreezes.
In addition, if there is enough moisture in the atmosphere and the cubes are cold enough, some water can freze right out of the atmosphere, filling in the gaps between the cubes.
What I’m not at all sure of is the relative importance of the pressure effect and the simple reduction of surface area effect. Also, I’m not sure how about the relative imporatnce of the vapor and of the surface liquid in moving molecules around.
Mike W.
You can check the hypothesis that moisture from the air is condensing on your ice cubes and then freezing by looking for fuzzy frost on your ice cubes. Another idea of what could be going on is that your ice cubes are melting a bit and then re-freezing if the temperature in your ice bucket goes through cycles of warming and cooling. This will certainly speed up the process of clumping ice cubes together.
Tom
(published on 10/22/2007)