At what temperature does water freeze

At what temperature does water freeze? It would seem - the simplest question, which even a child can answer: the freezing point of water at a normal atmospheric pressure of 760 mm Hg is zero degrees Celsius.

However, water (despite the extremely widespread its on the planet) is the most mysterious and not fully studied substance, so the answer to this question requires a thorough and reasoned conversation.

• In Russia and in Europe, the temperature is measured on a Celsius scale, the highest value of which is 100 degrees.
• The American scientist Fahrenheit developed his scale, which has 180 divisions.
• There is another temperature measurement unit, Kelvin, named after the English physicist Thomson, who received the title of Lord Kelvin.

States and types of water

Water on planet Earth can take three basic state of aggregation: liquid, solid and gaseous, which can transform into different forms that simultaneously coexist with each other (icebergs in sea water, water vapor and ice crystals in the clouds in the sky, glaciers and free flowing rivers).

Depending on the origin, purpose and composition of the water can be:

• fresh;
• mineral;
• nautical;
• drinking (here we will carry tap water);
• rain;
• thawed;
• brackish;
• structured;
• distilled;
• deionized.

The presence of hydrogen isotopes makes water:

1. easy
2. heavy (deuterium);
3. super heavy (tritium).

We all know that water is soft and hard: this indicator is determined by the content of magnesium and calcium cations.

Each of the types and aggregative states of water that we have listed has its own freezing and melting point.

Water freezing point

Why does water freeze? Plain water always contains some suspended particles of mineral or organic origin. It may be the smallest particles of clay, sand or house dust.

When the ambient temperature drops to certain values, these particles take on the role of centers around which ice crystals begin to form.

Air bubbles can also become nuclei of crystallization, as well as cracks and damage to the walls of the vessel containing water. The speed of the process of crystallization of water is largely determined by the number of these centers: the more of them, the faster the liquid freezes.

Why does hot water freeze faster than cold?

Hot water freezes faster than cold — Erasto Mpemba, a schoolboy from Tanganyika, noticed this phenomenon. His experiments with the mass for making ice cream showed that the speed of freezing of the heated mass is much higher than the cold one.

One of the reasons for this interesting phenomenon, called the “Mpemba paradox”, is the higher heat transfer of a hot liquid, as well as the presence of a larger number of crystallization nuclei in it compared to cold water.

Is the freezing point of water interconnected with altitude?

When the pressure changes, often associated with being at different heights, the freezing point of water begins to radically differ from the standard, typical of normal conditions. Crystallization of water at a height occurs at the following temperature values:

• Paradoxically, at an altitude of 1000 m, water freezes at 2 degrees Celsius;
• at an altitude of 2000 meters, this happens already at 4 degrees of heat.

The highest temperature of freezing of water in the mountains is observed at an altitude of over 5,000 thousand meters (for example, in the Fan Mountains or in the Pamirs).

How does pressure affect the crystallization of water?

Let's try to link the dynamics of change in the freezing point of water with a change in pressure.

• With a pressure of 2 atm, water will freeze at a temperature of -2 degrees.
• With a pressure of 3 atm, the onset of freezing of water will be a temperature of -4 degrees Celsius.

That is why in the conditions of high mountains and rarefied atmosphere it is very difficult to boil even eggs, since the water in the pot boils already at 80 degrees. It is clear that at such a temperature it is simply impossible to cook food.

With high pressure, the process of melting ice under the blades of the skates occurs even at very low temperatures, but it is thanks to him that the skates slide on the ice surface.

Similarly, the freezing of runners of heavily loaded sleds in the stories of Jack London is explained. Heavy sleighs that put pressure on the snow cause it to melt. The resulting water facilitates their sliding. But it is worth stopping the narts and stay for a long time in one place, as the displaced water, having frozen, will freeze the runners to the road.

The crystallization temperature of aqueous solutions

Being an excellent solvent, water easily reacts with various organic and inorganic substances, forming a mass of sometimes unexpected chemical compounds. Of course, each of them will freeze at different temperatures. Reflect this in a visual list.

• The freezing point of a mixture of alcohol and water depends on the percentage ratio of both components in it. The more water added to the solution, the closer to zero its freezing temperature. If more alcohol is in the solution, the crystallization process will begin at values ​​close to -114 degrees.

  It is important to know that water-alcohol solutions do not have a fixed freezing temperature. Usually they say about the temperature of the beginning of the crystallization process and the temperature of the final transition to the solid state.

  Between the beginning of the formation of the first crystals and the complete solidification of the alcohol solution lies a temperature interval of 7 degrees. So, the freezing point of water with alcohol of 40% concentration at the initial stage is -22.5 degrees, and the final transition of the solution into the solid phase will occur at -29.5 degrees.

To measure the salinity of water use a special unit - "ppm." So, we have found that the freezing point of water decreases with increasing salt concentration. Let us explain this with an example:

The salinity level of ocean water is 35 ppm, while the average value of its freezing is 1.9 degrees. The degree of salinity of the Black Sea waters is 18-20 ppm, so they freeze at a higher temperature with a range from -0.9 to -1.1 degrees Celsius.

• The freezing point of water with sugar (for a solution whose molality is 0.8) is -1.6 degrees.
• The freezing point of water with impurities depends largely on their quantity and the nature of the impurities that make up the aqueous solution.
• The freezing point of water with glycerin depends on the concentration of the solution. A solution containing 80 ml of glycerin will freeze at -20 degrees, while reducing the content of glycerol to 60 ml of the crystallization process will begin at -34 degrees, and the beginning of the freezing of the 20% solution - minus five degrees As you can see, there is no linear relationship in this case. For freezing a 10% solution of glycerin, a temperature of -2 degrees will suffice.
• The freezing point of water with soda (implying a caustic alkali or caustic soda) is a more mysterious picture: the 44% caustic solution freezes at +7 degrees Celsius, and 80% - at + 130.

Freshwater freezing

The process of ice formation in freshwater bodies of water occurs in a slightly different temperature.

• The freezing point of water in the lake, just like the freezing point of water in the river, is zero degrees Celsius. Freezing of the cleanest rivers and streams does not begin from the surface, but from the bottom, where crystallization nuclei are present in the form of bottom sludge particles. At first, snags and aquatic plants become covered with a crust of ice. As soon as the bottom ice rises to the surface, the river instantly freezes through.
• The frozen water at Baikal can sometimes be cooled to negative temperatures. This happens only in shallow water; water temperature can be in the thousandth, and sometimes hundredths of one degree below zero.
• The temperature of the Baikal water under the crust of the ice cover, as a rule, does not exceed +0.2 degrees. In the lower layers, it gradually rises to +3.2 at the bottom of the deepest basin.

Distilled water freezing point

Does distilled water freeze? Recall that for the freezing of water requires the presence in it of some crystallization centers, with there may be air bubbles, suspended particles, and damage to the walls of the tank in which it located.

Water subjected to very low temperatures, but not crystallized, is called “supercooled”. You can put a bottle of distilled water in the freezer, get it hypothermia, and then demonstrate a very effective trick - see the video:

By tapping the bottle extracted from the refrigerator, or throwing a small piece of ice into it, you can show how instantly it turns into ice, having the appearance of elongated crystals.

Distilled water: does this purified substance freeze or not under pressure? Such a process is possible only in specially created laboratory conditions.

Salt water freezing point

1. Does salt water freeze? Due to the high salt concentration, ocean and sea water freezes at a temperature of -1.9 degrees Celsius.
2. The temperature of freezing of water in the seas and oceans does not have a constant value, since the salinity of the water in different seas of the oceans is completely different.
3. How does the freezing point of ocean water depend on its salinity? There is a direct connection between these values. The more salty the water is, the higher its density is, and a sufficiently low temperature is required to freeze such water.
4. The average temperature in the seas and oceans is -4 degrees.

Freezing point of individual seas

With how many degrees does water freeze:

• The Caspian Sea? The salinity of the Caspian waters is about 13 ppm. Their freezing occurs at -0.5 degrees Celsius. The thickness of the ice cover of the northern part of the Caspian Sea is about two meters.
• Sea of ​​Azov? Its salt water freezes at a temperature of -0.5 to -0.7 degrees Celsius. Salinity is about 11 ppm. The thickness of the ice covering the sea from December to March is one meter.
• Sea of ​​Japan? Why does the salt water of this sea not freeze? This is due to the high (about 34 ppm) level of its salinity and the geographical position of the sea.
• The Baltic Sea? With a salinity of only 6–8 ppm, the freezing temperature of sea water in the Baltic is close to zero.

Express Answers

With how many degrees does water freeze:

1. In the heating pipes? In the event of a heating shutdown or a heating boiler breakdown in a private house or country house, water may freeze in them in about a couple of days at a temperature of -5 degrees. To delay the onset of such an outcome will help thermal insulation of pipes and other elements of the building. Inside the dwelling, water freezing in the pipes begins at -1 degrees. If this temperature lasts 2-3 days, it may end up breaking pipes and heating batteries.
2. Underground? Groundwater can be liquid, solid and vapor. The solid phase of water in the soil is ice, which can be both long-term (in permafrost conditions) and seasonal. Freezing of soil waters occurs at temperatures below zero, since all of them are not pure water, but all sorts of its solutions. The value of the freezing temperature depends largely on the salinity of groundwater.
3. On the fly? The inhabitants of Yakutia have a simple way to determine the temperature of the air: it is below -42 degrees, if the spittle released by a man has time to freeze before reaching the ground.
4. In a vacuum? The contents of the tube, placed under the bell of the vacuum pump at a temperature of 0 degrees, first boils, and after evaporation of the eighth part of the liquid ice crust forms on its surface.
5. In the car engine? The maximum temperature of freezing of water in the engine can reach -5 degrees: at lower values, ice crystals will simply break the internal structure of the engine block. Just the same is the freezing point of water in the radiator. Similar problems in the car can occur if there is insufficient insulation of the above units, as well as due to too long parking.
6. On the rink? Depending on what competitions are supposed to be held on the ice arena, the temperature of the ice surface can be from -3 to -5 degrees. Ice with a higher (from -3 to -4) surface temperature is suitable for figure skating, since it is its softness that allows for the necessary strength of adhesion with the skates. More hard ice, suitable for team hockey, is obtained at a temperature of -5 degrees. On the "cold" ice, the speed of the players increases and the possibility of the formation of snow "porridge" on its surface decreases. The quality of ice primarily depends on the chemical composition of water, therefore, to fill it, use not ordinary liquid from the tap, but either purified or treated water with special conditioners.