What is Ice?
{{for|water in its [[liquid|liquid state]]|Water}} [[File:Ice, Sea ice, Frozen Sea of Azov, Russia.jpg|thumb|Sea ice]] [[File:Loneliness, solitude in snow storm, Don River in ice, Rostov-on-Don, Russia.jpg|thumb|right|River ice]] [[File:Ice crystals at refrigerator window.JPG|thumb|right|Crystals of ice on [[glass]]]] '''Ice''' is the [[common name]] for frozen [[water]]. Other [[liquid]]s, such as [[ammonia]] or [[methane]] or [[milk]], are called 'milk ice', for instance, instead of just 'ice'. Liquid water becomes [[solid]] '''ice''' when it is very cold. The [[freezing point]] is 0° [[Celsius]] (32° [[Fahrenheit]] or 273 [[kelvin]]). Ice can be made in a home [[refrigerator]] or freezer. If water is put in a freezer and left for a while, the water gets very cold and will freeze solid, creating ice. Water can be placed into a [[copper]] (or other [[metal]]) [[container]] to cause it freeze into ice faster. Water can freeze faster than in a [[plastic]] ice [[tray]]. == How ice is formed == Unlike other liquids, water expands as it freezes to become ice. It floats on water because ice has less [[density]] than water. This is very unusual {{ndash}} most liquids gets more dense as they cool: water ice is an exception. Liquid water expands by about 9% as it becomes ice – it takes up more space. This is because the water molecules are actually farther apart instead of being closer together. The molecules in an ice crystal are arranged in a way that makes it less dense than liquid water. If water in [[plumbing]] freezes, it can burst the [[pipe (material)|water pipe]]. Water in [[glass]] [[bottle]]s can make them explode when it freezes. Water freezing in rock cracks can expand enough to split hard [[Rock (geology)|rocks]] apart; this is an important geological [[weathering]] [[process]] that can wear down [[mountain]]s and make rock into [[soil]]. == Salt water == [[Salt water]] needs a lower temperature to freeze than pure water. Most of the salt does not enter the ice, so the resulting ice is less salty tha