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 oneeleventh 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 Hard Water: Dissolved Minerals Water is so good at dissolving other substances that apart from distilled water, it’s seldom found in anything like pure form Tap water is quite variable in composition, depending on its ultimate source (well, lake, river) and its municipal treatment (chlorination, fluoridation, and so on) Two common minerals in tap water are carbonate (CO3) and sulfate (SO4) salts of calcium and magnesium Calcium and magnesium ions are troublesome because they react with soaps to form insoluble scums, and because they leave crusty precipitates on showerheads and teapots Such so-called hard water can also affect the color and texture of vegetables, and the consistency of bread dough (pp 282, 535) Hard water can be softened either city-wide or in the home, usually by one of two methods: precipitating the calcium and magnesium by adding lime, or using an ion-exchange mechanism to replace the calcium and magnesium with ... composition, depending on its ultimate source (well, lake, river) and its municipal treatment (chlorination, fluoridation, and so on) Two common minerals in tap water are carbonate (CO3) and sulfate (SO4)... Such so-called hard water can also affect the color and texture of vegetables, and the consistency of bread dough (pp 282, 535) Hard water can be softened either city-wide or in the home, usually by one of two methods:... salts of calcium and magnesium Calcium and magnesium ions are troublesome because they react with soaps to form insoluble scums, and because they leave crusty precipitates on showerheads and teapots