What is the principle of edible salt as a snow melting agent?

Principle: The freezing point of sodium chloride snowmelt agent dissolved in water (snow) is below zero, that of sodium chloride snowmelt agent dissolved in water is-10℃, and that of salt water is lower than that of water, so it is difficult to form ice cubes after salt is dissolved in snow water. In addition, after the snow melting agent is dissolved in water, the ion concentration in water increases, which makes the liquid vapor pressure of water decrease, while the solid vapor pressure of ice remains unchanged. In order to reach the solid-liquid vapor pressure state of the ice-water mixture, the ice melted. This principle can also explain why salt water is not easy to freeze.

The harm of snow melting agent to the environment;

1. It is very harmful to the green belt and farmland on both sides of the road.

Chlorine salt snow melting agent is convenient for snow melting and snow removal, and the price is also cheap. However, the snow after using snow melting agent often accumulates in green belts or farmland on both sides of the road. After the spring, its salt residue is all accumulated in farmland and green belt, which makes the soil salinized and destroys the vegetation.

2. Corrosion of roads, bridges and other road facilities

When salt meets water, the salt will rise, which will destroy the road subgrade and increase the difficulty of road maintenance. Chlorine salt permeates into concrete, which will promote the freezing and thawing of concrete. But its main destructive function is the corrosion of steel bars. When chloride ion reaches the surface of steel bar and exceeds a certain amount (critical value), the steel bar which was originally in a passive state will be activated and corroded.

3. Groundwater pollution

The commonly used snow melting agent is mainly salt, and the salt on the road surface melts the ice and flows with the snow water. After salt substances enter the ground, it will inevitably pollute the local groundwater resources.