What chemistry is used to sprinkle salt on the snow?

Because it can melt the snow.

Let's first understand some of the physical and chemical properties of table salt (the main ingredient NaCl) used in snow melting:

Solubility. Table salt dissolves easily in water, which is a very common physical phenomenon.

Moisture absorption. The surface of salt is usually surrounded by a thin film of saturated salt solution, when the vapor pressure of this film solution is lower than the partial pressure of water vapor in the air, the salt adsorbs the moisture in the air and deliquescent; On the contrary, when it is higher than the partial pressure of water vapor in the air, it is dry. Of course, this is only a phenomenon that occurs when salt is exposed to the air, and salt that is sealed in a bag and isolated from the surrounding air will not deliquescent;

The freezing point is low. The freezing point I am talking about here does not actually refer to the dissolution point of pure table salt (NaCl) crystals, because it has to be heated to thousands of degrees Celsius to melt without the participation of water, and the freezing point here refers to the freezing point of the salt solution, and experiments have shown that if the salt solution contains 20% salt, its freezing point will be reduced to -16

There are many other properties of table salt, but to explain this problem, there are a few above are almost the same :) In addition, by the way, the composition of snow is mainly solid water - Xiaoice crystals, no matter how low the temperature, ice has the phenomenon of sublimation, so water vapor is diffused around the snow.

When we sprinkle salt on the snow, the salt uses its moisture-absorbing properties to absorb water vapor from the surface of the snow, thus increasing its own strength"tide"The film of the salt solution is becoming more and more obvious, and I think that the solution layer at this time is like a spark"Invasion"The surrounding snow layer eventually turned against the guest and wiped out all the snow.

Salt is sprinkled on the snow so that the freezing point of the dilute solution is lower than that of water.

Salt is sprinkled on the snow to lower its freezing point, and when it is lower than the ambient temperature, it melts

I'm a master

Frictional heat causes the snow to melt.

Lowers the freezing point of the snow so that it melts faster.

The salt sprinkled on the snow is snowmelt salt. Snow melting salt refers to sodium chloride, calcium chloride, magnesium chloride, potassium chloride, etc., which are dissolved in water (snow) and have a freezing point below zero. Salt causes wild water to freeze lower than water, so it is difficult to form ice after the salt is dissolved in the snow water.

The snow melting agent was once known as "ice salt", and chloride salt snow melting agent is used more in countries around the world. <

Physical and chemical properties of snowmelt salt: 1. Solubility: easy to dissolve in water, a common physical phenomenon.

2. Moisture absorption: the surface of the snowmelt salt is usually surrounded by a film-like saturated salt solution, when the vapor pressure of this film solution is lower than the partial pressure of water vapor in the air, the sprite salt adsorbs the moisture in the air and deliquescent; On the contrary, when it is higher than the partial pressure of water vapor in the air, it is dry. Of course, this is only a phenomenon when the snow melt salt is exposed to the air, and the snow melt salt sealed in the bag and isolated from the surrounding air will not deliquescent.

3. Low freezing point: Experiments have shown that if the snowmelt salt solution contains 20% salt, its freezing point will be reduced to slippery silver-16.

It starts with the chemical composition of the salt. The composition of salt is sodium chloride, and the composition of snow is water. Sodium chloride is a chemical that is extremely soluble in water.

When sodium chloride is dissolved in water, it produces an aqueous solution of sodium chloride, which contains sodium ions and chloride ions. When it is to freeze, when chloride ions and sodium ions are present, chloride ions and sodium ions will destroy the crystalline structure of the water, so that the water cannot freeze. That is, sprinkling salt is good for the melting of snow.

Besides, salt is cheap and free of pollution. Therefore, when it snows, salt the road surface is often sprinkled with salt to prevent the snow from freezing. ,8,Why does sprinkling salt on the road make snow melt quickly?

In winter, sprinkling salt on the road can make the snow melt quickly, what is its chemical principle?

The main chemical component of salt is sodium chloride, and if it is table salt, there is a small amount of potassium iodate and sodium carbonate in early change. When the snow is sprinkled with sodium chloride, because the sodium chloride is very soluble in water, the surface of the snow has a layer of sodium chloride solution. The freezing point of water (also called the freezing point) is zero, and when sodium oxide is dissolved in the water, the freezing point of salt water is greatly reduced, to minus ten or twenty degrees.

Taking advantage of this characteristic of salt water, people can use the method of sprinkling salt to prevent the road surface and airport runway from freezing in the cold winter when the dripping water becomes ice.

In terms of molecular structure, when sodium chloride is dissolved in water, it ionizes into sodium ions and chloride ions. When water is about to freeze, when chloride ions and sodium ions are present, chloride ions and sodium ions will destroy the network structure of water crystals, so that the water cannot freeze. In other words, salt keeps snow from freezing.

At the same time, salt is a fine crystal that increases the coefficient of friction on the road surface and reduces tire slippage. In addition, salt is also a cheap and non-polluting substance, so salt is generally sprinkled as a road surface snow dissolving agent.

In order to increase the condensation nucleus, it is similar to the principle of artificial rainfall, the dry ice (solid carbon dioxide) hit into the air, when the dry ice melts, the heat absorption can reduce the temperature and increase the supersaturation of the water vapor in the dark clouds, and another function is to provide the condensation nucleus, so that the water vapor becomes raindrops.

If there are no porcelain tiles, the water temperature in the boiler is very high and will not become bubbles for heat dissipation, and the water temperature may be much higher than 100 degrees, which will eventually cause **.

If there is no salt, the ambient temperature is not easy to melt even if it is higher than 0 degrees, after the salt is sprinkled, the condensation nucleus is provided, and the temperature is slightly higher than 0 degrees to melt, and the melting point of the brine solution is generally lower than 0 degrees, and the two reasons combine to make it easier to melt snow when salt is sprinkled.