Why should the road be salted when it is frozen?

Spray salt on the pavement to lower the freezing point of water. The melting point of any water solution is lower than that of water under the same conditions.

The anti-skid effect of salt itself is not obvious. When it snows, salt is sprinkled because the freezing point of salt water is higher than that of pure water. The higher the concentration of salt water, the lower the freezing point, so that the snow can melt faster, thus achieving the anti-skid effect.

Just as the freezing point of seawater is lower than pure water, the density of water increases after salt is sprinkled, and it is not easy to freeze and become water to walk away or evaporate.

Extended data:

Reasons for road icing:

1. If the ground temperature is lower than 0℃, snow or ice will appear on the road surface.

2. Freezing on the road surface is easy to occur from June 165438+ 10 to April of the following year (that is, winter and early spring).

3. Road icing often occurs in northern China. In the south of China, snowfall is generally "wet snow", which turns into ice water paste when it falls to the ground. When the temperature drops at night, it will solidify into chunks of ice. As long as the local minimum temperature in winter is below 0℃, road icing may occur.

As long as the temperature does not rise enough to melt the ice, the ice will remain hard. Generally speaking, in the cold winter, when the temperature drops due to a wide range of strong cold air activities (called cold wave in meteorology), if it is accompanied by rain and snow, it is most prone to road icing.

Baidu encyclopedia-road icing