Why does water freeze What happens when water freezes?

Generally speaking, when the temperature of water drops to 0, it will freeze, so is it true that all water will freeze once the temperature drops to 0? Not necessarily.

When meteorologists observed the clouds, they found a kind of mixed cloud, the temperature of the middle and upper part of the cloud has dropped to 20 to 30, or even 40, and there are many raindrops that are not frozen. It is said that there are scientists who have succeeded in cooling pure and flawless water to 70 years without freezing into ice. This kind of water that does not freeze when the temperature is below 0 is called supercooling water.

It turns out that the freezing of water molecules, in addition to temperature conditions, requires the presence of frozen nuclei in the water. With the frozen nucleus, the water molecules are arranged in the crystalline structure of the ice. The water of rivers, lakes and seas, and the tap water used in cities all contain impurities, and these impurities are frozen nuclei.

So when it reaches zero degrees Celsius, it freezes. However, for pure water, even if the temperature is below 0, it is difficult to freeze because there is no freezing core, and it cannot become ice. If you put some small ice crystals, or sand grains in a glass of pure water, the water molecules have a core or are attached to the crystal structure of the ice, and they become ice.

In nature, it can be seen that cooling water freezes quickly when it hits an object. In the middle of winter, in the north of our country, you can see a strange phenomenon, what falls from the sky is obviously raindrops, but there is no trace of rain on the ground, and all you see is ice. The rain quickly formed a layer of crystal clear ice on the branches and power lines, and gradually hung down into icicles.

This kind of rain that drops into ice is called freezing rain, and the ice formed by raindrops is called rime.

When the temperature is high, the water molecules are in constant motion and the water can flow. The lower the temperature, the less intense the molecular movement becomes. When the temperature is as low as freezing, the water molecules basically do not move, and stop because the distance between the molecules increases a little and shows gravity, so the water does not flow, and the volume of ice is one-tenth larger than that of water.

From a macro point of view - the water freezes.

Yes, the details are as follows:Curing: snowflakes, ice, frost, frozen lake surface.

Liquefaction: rain, snow, flooding. Gasification:

Water vapor from boiling water (evaporation phenomenon). Water is one of the most common substances on Earth. 71% of the Earth's surface is covered by water.

It is an important resource for the survival of all life, including inorganic chemistry and human beings, and it is also the most important component of living organisms.

Water is a colorless, tasteless, and odorless liquid at room temperature.

The density of water is the highest (1000 kg m is often taken in approximate calculations). The density of solid water (ice) is smaller than that of liquid water, so ice can float on the water. When the water freezes, the volume increases slightly.

South-to-North Water DiversionChina's water shortage mainly refers to the north. In particular, in the past 20 years, due to natural changes and the impact of human activities, the trend of more freshwater resources in the south and less in the north has become more serious. The distribution of freshwater resources formed by natural, geographical, meteorological and other factors is difficult to solve by soft science alone.

It has to be done in a hard way. The ongoing South-to-North Water Diversion Project is one of the hard ways.

The above content is from Encyclopedia-Water

Hexagonal crystalline ice is produced when liquid water is cooled to below 0 °C (, 32 °F) at standard atmospheric pressure (1atm).

When the water freezes, it increases in volume by about 9. The effect of water expansion when it freezes is extremely huge, and ice expansion is the basic cause of freeze-thaw weathering in weathering phenomena, and it will also cause damage to building foundations and road bumps and lifts. Water pipes burst due to the pressure of the freeze and are also a common cause of water leaks in the house.

When ice melts, it absorbs about 80 of the same mass of water as it heats up. During the melting process, the temperature is kept at 0 constantly. When melting, the energy added by the outside world is used to break the hydrogen bonds between the ice (water) molecules.

Only when enough hydrogen bonds have been broken and the ice has become so weak that it can be treated as liquid water will the added energy increase the heat (temperature). In the process of changing from ice to water, the energy expended to break the hydrogen bonds is known as the heat of fusion.

1. After reaching the freezing point, the movement of water molecules slows down, and the gravitational force between molecules makes the slowed water molecules slowly arrange in an orderly manner. In a high-temperature environment, the molecular energy is also large, and the active area is also large, so it will exist in the form of liquid or gas. Because the environment in which people live is mainly above zero and below zero, they subconsciously feel that water should be liquid, just as people have always thought that iron is solid, if the ambient temperature around them is 1,000 degrees, then subconsciously they will also feel that iron is liquid like water;

2. When the temperature drops, the molecular energy will release heat into the surrounding environment according to the law of conservation of energy, the activity of the molecules will decrease, and the distance between the molecules will get closer and closer, and then it will be arranged according to the molecular formula of water, and when it reaches zero degrees, it will condense into a solid, that is, ice cubes. Of course, at this time, the molecules are still active, and the atoms of the hydrogen and oxygen elements are still moving around the protons, and when they reach absolute zero, the molecules and atoms of all objects really stop moving.

Water condenses from a liquid state to a solid state below 0 degrees Celsius, which is called freezing.

It is important to note that:

0 degrees Celsius generally does not freeze. 0 degrees is the freezing point. If there are no impurities, it will freeze at 0 degrees, and if there are impurities, it will freeze at 0 degrees or less, about minus 3 degrees.

The density of water below -4 degrees Celsius increases and the volume increases, and if you put water in a bottle in winter, there is a high risk that the bottle will crack due to the increase in volume.

Water freezing is the process of water from amorphous to crystalline, when reaching the freezing point, the movement of water molecules slows down, and the gravitational force between molecules makes the slower water molecules slowly arrange in an orderly manner, after arrangement, the movement space of water molecules becomes smaller, and orderly, macroscopically become a relatively stable crystalline shape.

Water freezing is the process of water changing from amorphous to crystalline, which can be explained by molecular motion theory: after reaching the freezing point, the movement of water molecules slows down, and the gravitational attraction between molecules makes the slower water molecules slowly arrange in an orderly manner.

The tri-state change of a common substance: the temperature of the substance is higher than the melting point, the substance becomes liquid, and above the boiling point, it becomes gaseous. Water is liquid at room temperature, and when the temperature of the water is lower than a certain value (0 degrees Celsius under standard conditions), the water temperature is below the melting point and condenses into ice.