Add salt to the crushed ice, and after a few minutes, find out what happened to the water in the test tube.

After adding salt to crushed ice, it is found that the water in the test tube will increase in a few minutes, and the freezing point of crushed ice can be lowered after sodium chloride is dissolved in water, so the freezing point of crushed ice can be lowered below the temperature after adding sodium chloride to accelerate the melting of ice.

Resulting in a lower melting point. Seawater is water with dissolved salt, and the freezing temperature of seawater is lower than that of river water in winter, which is the reason. The melting point of saturated brine can be reduced to about -22℃, and salt is often sprinkled on roads in northern cities when it snows heavily in winter.

Extended data:

In order to minimize the impact of snow and ice weather on urban order, there will be many sanitation workers and snow sweepers on the roads in the early hours of the morning. In addition, there will be a special salt spreader to sprinkle salt on the snowy roads.

Only when the temperature is below a certain temperature will it snow in the sky. When the ambient temperature is higher than this temperature, the snow on the road surface will melt. Physically, the temperature we need to melt an object into a liquid is called the melting point. The melting point of normal snow is 0℃. After sprinkling salt into the snow, the melting point will change, which is no longer 0℃, thus making the snow on the road surface melt faster.