Wondering Why?

Why Do Ice Cubes Shrink In The Freezer?

Why Do Ice Cubes Shrink In The Freezer?

Ice cubes shrink when left in the freezer for a long time because of the process of sublimation. This is occurs when a solid mass changes directly into gas. This occurrence is not at all unusual for there are substances and conditions that make this happen.

This is common occurrence in most frost-free refrigerators. The ice is kept in a below-zero condition maintaining its solid state but is still exposed to low humidity conditions with air coming in and out of it. The air melts the ice just a little bit without us seeing it. The water molecules on the surface of the ice join the water molecules in the air surrounding it.

Frost-free refrigerators of today speeds up this process because the gas molecules do not remain inside the fridge long enough to envelope the whole area with ice crystals. Instead, it is sucked out of the freezer compartment where they end up condensing and freezing in the evaporator coil.

Sublimation is one change of phase that can be considered to be awesome. It is almost like evaporation but in a different medium. The liquid molecules in the surface of the ice cube jump of to join the gas molecules floating in the air around them. The transformation of the liquid molecules into gas cause the ice cubes to shrink over time. It does not occur instantly because only a thin layer of the ice is transformed into gas.

However, when you leave your ice cubes undisturbed for quite some time, you will see that it has indeed shrunk. The worse thing that can happen is that it has taken in the flavors and odors of the other things in the freezer. So the next time you go on vacation check first your ice cubes before using it to cool your drink when you get back.

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2 Submissions

  1. From wikipedia (http://en.wikipedia.org/wiki/Sublimation_%28phase_transition%29)

    Sublimation is the transition of a substance from the solid phase to the gas phase without passing through an intermediate liquid phase.

    So, “The air melts the ice just a little bit without us seeing it” doesn’t quite fit with sublimation definition.

  2. Ice, water, and water vapor coexist at the triple point of 611.3 Pascal (0.006 atm, very low pressure) and 0.01 Celsius. Ice can’t sublime in the freezer because it’s above 611.3 Pascal.

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