✔ 最佳答案
While there are various theories being debated as to the exact scientific explanation of the phenomenon, many scientists claim that it is a physical reaction and not a chemical one. Water molecules strongly attract each other, linking together to form a tight connection around each bubble of carbon dioxide gas in the soda. To form a new bubble, water molecules must push away from one another. It takes extra energy to break this surface tension. So, in other words, water resists the expansion of bubbles in the soda.
When Mentos are dropped into soda, the gellan gum and gum arabic of the candy dissolves and breaks the surface tension. This disturbs the water connection, so that it takes less work to expand and form new bubbles. Each Mentos candy has thousands of tiny pores all over its surface. These tiny pores function as nucleation sites, perfect places for carbon dioxide bubbles to form. As soon as the Mentos enter the soda, bubbles form all over their surface. They quickly sink to the bottom, causing carbon dioxide to be released by the carbonated liquid with which they come into contact along the way. The sudden increase in pressure pushes all of the liquid up and out of the bottle.
The reaction was the subject of an August 9, 2006 episode of MythBusters, a television program on the Discovery Channel. They concluded that the caffeine, potassium benzoate, aspartame, and CO2 gas contained in the Diet Coke and the gelatin and gum arabic ingredients of the Mentos all contribute to the geyser effect. In addition, the MythBusters theorized that the physical structure of the Mentos is the most significant cause of the eruption. When flavored Mentos with a smooth waxy coating were tested in carbonated water, no reaction occurred, whereas standard Mentos added to carbonated water formed a small geyser, by their claim, affirming the nucleation-site theory. Of course a wax coating would render just about anything inert in this experiment; wax-coated sodium would have given the same reaction. This was further supported when rock salt was used as an effective substitute for Mentos. The experiment was also repeated in an episode from Numb3rs.