Ice Damages Cells

Normally, the solid phase of a given substance is denser than the liquid phase. As the molecules’ attraction for each other becomes stronger than their movements, the molecules settle into a compact arrangement determined by their geometry. In solid water, however, the molecular packing is dictated by the requirement for even distribution of hydrogen bonds. The result is a solid with more space between molecules than the liquid phase has, by a factor of about one-eleventh. It’s because water expands when it freezes that water pipes burst when the heat fails in winter; that bottles of beer put in the freezer for a quick chill and then forgotten will pop open; that containers of leftover soup or sauce will shatter in the freezer if they’re too full for the liquid to expand freely. And it’s why raw plant and animal tissues are damaged when they’re frozen and leak liquid when thawed. During freezing, the expanding ice crystals rupture cell membranes and walls, which then lose internal fluids when the crystals melt.