In order to make the snow melt faster, people usually sprinkle some grass ash on the snow, and that

Accelerates snow melt.

2 more points:

First of all, the snow melts and turns into water, and the ash of plants and trees is alkaline, and most of the alkali dissolves in water to produce heat. Is this one of the factors? You go and check the composition of the plant ash to see if this factor is true. I guess it's negligible, but you can look it up or ask the teacher to broaden your knowledge.

1. Plants and trees are gray and black, will not produce refraction and reflection, and absorb sunlight better than ice and snow, so it heats up quickly and melts quickly.

2. Grass ash can absorb the water from the ice, which has 4 benefits, one: water will reflect sunlight, and the junction of water and ice will also reflect sunlight. So the ice that sucks the water off melts faster than the ice-water mixture.

2. The conduction of water to heat generally depends on convection. If you soak your hands in hot water, they won't be hot for a while, but when you stir the water, your hands will feel hot again, because the water forms a thermostatic layer around your hands, which is not conducive to heat conduction.

Three: the specific heat capacity of water is larger, and the temperature rises slowly, so the temperature rises quickly after the plant ash absorbs water.

Four: The evaporation of water will take away the heat, and the more it evaporates, the more heat it takes away. If you try to pour the same amount of water on the concrete floor as on the soil, you should know which case the water will evaporate faster.

Relative to the surrounding white snow, grass and wood ash.

It's black and absorbs heat, so the snow around melts quickly.

Salt melts snow because the surface of the crystallized snow is covered with a thin layer of salt solution. And when any substance is dissolved in water, it can reduce the freezing point of water (zero degrees Celsius). As the temperature decreases, the speed at which the molecules in the liquid move gradually slows down.

As the temperature decreases, the speed at which the molecules in the liquid move gradually slows down and the distance between the molecules gets closer and closer. Eventually, when the speed slows down to the point where the forces between the molecules outweigh the energy generated by the motion of the molecules, the molecules accumulate to form a solid, and the water becomes ice. We call the temperature at the time of this phenomenon freezing.

If salt is added, the structure of the water molecules in the snow is destroyed. As an American scientist pointed out, "The gravitational attraction between water molecules is disturbed by salt, and the formation of its solid state is hindered." "Because the salt molecules get in the way, the water molecules can't gather to form snow, so the snow melts away quickly.

The freezing point of salt is -10 after dissolving in water, and in addition to endothermy for the dissolution of salts, another effect is that the freezing point of salt water is low, so it is difficult to form ice cubes after dissolving salt in snow water. When dissolved in water, the concentration of ions in the water increases, causing the liquid vapor pressure of the water to decrease, but the solid vapor pressure of the ice remains unchanged. In order to achieve the solid-liquid vapor pressure of the ice-water mixture, the ice melts.

This principle is also a good explanation for the fact that salt water does not freeze easily.

We know that water is a special substance, that is, the density becomes less after freezing (the density of the general substance in the solid state is greater than the density in the liquid state), therefore, the greater the pressure, the lower the melting point of the ice. It is often seen that where the wheels run over the snow, the snow tends to melt easily. When a snow-covered road surface is sprinkled with a snow melting agent, it is easier for the snow to melt when it is crushed by vehicles.

The solid substance is dissolved in water, and the boiling point of the resulting solution is higher than that of pure water, and the freezing point is lower than that of pure water; When salt is sprinkled on top of the snow, the freezing point of the salt solution formed when the salt is dissolved in water is lower than that of water, so that the snow and ice can melt even at lower temperatures

Therefore, the answer is: the freezing point of salt dissolved in water to form a solution is lower than that of water

When other conditions are equal, sprinkling salt water on the snow is equivalent to mixing impurities, and the melting point of the snow is reduced, so that the snow melts and the transportation is convenient

So the answer is: melting point

1. After sprinkling salt, condensation nuclei are provided, and as long as the temperature is slightly higher than 0 degrees, the snow will begin to melt.

2. The freezing point of salt water is generally lower than 0 degrees, which is easier to melt snow.

3. Because the freezing point of salt water is lower than that of water.

4. The water absorption of salt is also the reason why snow is easy to melt.

Because snowflakes are pure, when salt is added, they become a dilute solution of electrolyte that is difficult to volatile, so the freezing point is reduced and melts quickly.