From Simple English Wikipedia, the free encyclopedia
Water dripping from a slab ofice and then freezing, formingicicles
Freezing is the process when aliquid changes into asolid because its temperature gets colder than a certain point called thefreezing point. When a liquid freezes, its molecules slow down because they loseheat energy. Then, the molecules line up in a neat and fixed pattern to form asolid. This change from liquid to solid is very important in many parts ofnature andtechnology. For example, freezing affects theweather, helps keepfood fresh, and is important in makingmaterials and inliving things. Freezing is the opposite of melting, and when it happens, heat is released from the liquid as it turns solid. The freezing point is the exact temperature where a liquid and its solid form can exist together without changing. This usually happens atnormal air pressure, like the pressure around us. For pure liquids, like pure water, the freezing point is always the same temperature. But formixtures, like salty water, the freezing point can change depending on what is mixed in. This is why salty seawater freezes at a lower temperature than pure water. Other things, like dirt or tiny particles (callednucleating agents), and changes inpressure can also affect how and when a liquid freezes by helping or slowing down the waycrystals form.[1][2]
Freezing happens in two main steps: nucleation and growth.Nucleation is the very first step, where tiny groups of molecules come together to form a small solid "seed." This seed is stable enough to start growing bigger. Nucleation can happen in two ways. Sometimes it happens inside the liquid by itself (called homogeneous nucleation). Other times, it happens onsurfaces or on tiny impurities, likedust particles, which help crystals form (called heterogeneous nucleation). How fast freezing happens and what kind of crystals form depends on things like how quickly the liquid cools down, how pure the liquid is, and whether there are other substances mixed in. Scientists use this knowledge to control freezing in things likefood storage and makingmedicines.[3]
Freezing is very important for nature and theEarth's climate. When water freezes inoceans,lakes, andrivers, it affects theanimals andplants living there. It also helps control how heat moves around theplanet. Freezing happens every season and changes thesoil, which affects how plants grow. Scientists also use freezing to help save biological samples andorgans, a process calledcryopreservation.[4] Freezing water is also part of many weather events, likefrost on the ground,hail falling from the sky, andsnow forming in theclouds.[5] Freezing is very useful intechnology and everyday life. For example, freezingfood helps keep it fresh for a longer time. When food is frozen,bacteria andenzymes that cause spoilage slow down or stop working, so the food stays good.[6] Freezing is also used in different industries. It helps infreeze drying food, makingmetal andplastic parts, and producing very cold fuels calledcryogenic fuels. Knowing how freezing works and controlling it is important in many areas, fromfarming to buildingairplanes androckets.[7][8]
Freezing is a process where a liquid turns into a solid, and during this change,heat is released. This heat is called thelatent heat of fusion. Even though the liquid is cooling, its temperature stays the same while it is turning intoice until all of it has frozen.[9] Scientists have studied freezing a lot and have created special chemicals calledantifreeze agents. These antifreeze agents can change the freezing point of liquids, which means they stop ice from forming easily. Antifreeze is used incars to keep the engine from freezing in cold weather. It is also used to protect living things like plants and animals by stopping ice from damaging theircells.[10][11]
