Why do we need to spread salt on snowy days? The principle of spreading salt on snowy days

Snow is a natural phenomenon. It is the process of water vapor in the air condensing and falling back to the ground. Water is the basis for the existence of various organisms on the earth. The changes and movements of water have created the world we have today. After the snow, the road is very slippery and it is easy to cause traffic accidents. Now, whenever it snows, salt will be sprinkled, which can make travel as convenient as possible and bring faster recovery to production and life. Let's take a look at the principle of spreading salt when it snows!

Contents of this article

1. Why do we need to spread salt on snowy days?

2. The principle of spreading salt when it snows

3. The disadvantages of spreading salt when it snows

Why do we spread salt on snowy days?

After it snows, the road is very slippery, which can easily cause traffic accidents. Sprinkling salt on the road is because salt releases a lot of heat when it melts with water, which can melt the snow as quickly as possible and prevent the ground from freezing. If salt is sprinkled on the ice, the salt will melt with water and release heat, which will also melt the ice. This will enhance the friction of the ground and reduce the occurrence of traffic accidents.

The principle of spreading salt on snow

This starts with the chemical composition of salt.

Salt is made of potassium chloride, and snow is made of water. Potassium chloride is a chemical substance that is extremely soluble in water. When potassium chloride is dissolved in water, it forms a potassium chloride aqueous solution, which contains potassium ions and chloride ions. When water is about to freeze, when chloride ions and potassium ions are present, the chloride ions and potassium ions will destroy the crystal network structure of water, making it impossible for water to freeze. In other words, salt can prevent snow from freezing.

In addition, the chapter on vapor pressure in chemistry introduces: In fact, snow is constantly melting and solidifying, but the speed of the two is equal, so it always remains solid! We all know that the freezing point of salt water is lower than that of water. After sprinkling salt, the water around the snow becomes salt water, so it cannot solidify! In this way, the snow will continue to melt and cannot solidify back, so there will be less and less!

Besides, salt is cheap and does not pollute the environment. Therefore, when it snows, salt is often sprinkled on the road to prevent the snow from freezing. Salt can melt the snow.

However, because salt water can cause erosion to roads, many countries no longer allow the use of salt to melt snow, and instead use snow melting agents to melt the snow!

Disadvantages of spreading salt on snow

The salt components of melting snow are mainly potassium acetate and chloride salts, which can easily cause metal to rust when in direct contact with metal without a protective layer. This principle is the same as the fact that rust will quickly form on the inside of an iron pan if it is not cleaned and there is water.

There are certain anti-corrosion measures on the surface of the car body, mainly isolating the metal from contact with external substances, such as spraying paint on the surface of the car body, injecting wax into the cavity of the car body frame, etc. Under these conditions of complete protection, de-icing agents generally do not cause much damage to the car body, but if the protective layer is damaged, such as the paint surface of the car body is damaged (a small collision accident causes paint damage) and has not been treated for a long time, or the chassis is scratched due to the bottoming of the chassis, etc., it will cause the metal to directly contact with external substances, which may cause rust. The presence of de-icing agents will further aggravate this process.

Therefore, it is inevitable for vehicles in Northeast China to come into contact with snow-melting agents. However, as the temperature rises after the beginning of spring, car owners are advised to conduct a thorough cleaning of the car body including the chassis.