People think that the ice will melt faster in salt water because salt is sprayed on the road before it snows in winter. Students, even natural science professors, often think so! (This experiment was cited in a class where professors of natural sciences were gathered to teach pedagogy, but only one out of eight students was correct. Ah.. Of course, I already knew the answer, so it was excluded.)
The question of which water in tap water and salt water melts quickly... is directly related to density and density. Density is how much mass is contained in a certain volume. It's not an exact example, but if you have two boxes of apples of the same volume, and one box contains 100 apples and one box contains 10 apples, you can say that a box containing 100 apples is dense. Density is mass divided by volume. Then, shall we compare the density of tap water and salt water first?
First of all, if you compare tap water and salt water, tap water is just water... and salt water is salt water, so it's mass added! So, if you put water in an equal volume cup, the brine is denser.
Now... Then, let's think about the difference in density between cold and less cold water. As the ice melts, the water that comes out will of course be cooler, and the water in the cup is water that is similar to room temperature. (Salt water is also water with the same temperature.) So what is the relationship between temperature and density?
Have you ever blown a balloon in a warm room, brought it outside on a cold winter day and experienced the balloon wrinkled? Especially in the case of helium balloons, the store clearly blew and brought them out, but there are many times the balloons get soft while going to the parking lot in the cold winter. . When the temperature rises, the molecules have a lot of kinetic energy. So, the temperature affects the volume occupied by air. Assuming that the same amount of air is in the balloon, the volume of cold air is smaller than that of hot air, so the volume of cold water is also smaller. The smaller the volume, the higher the density value. The larger the denominator, the higher the density!
In the case of tap water with ice, the cold water from the ice sinks due to the heavy density, and in the process, the relatively less cold tap water on the bottom rises up, mixing the water. However, in the case of salt water, the density of cold water is smaller than that of salt water, so the cold water from the ice stays only on the surface of the water, and the ice slowly melts. So when I put the paint in, tap water could see the flow of water at a glance, while the salt water paint stayed only on the surface. (: Lee Sang was Lala's mom, who should go to oversee the exam soon!