On Oct. 6, 2010, during National 4-H Week, 24 youth ages 9 - 10 attended Science Day at the St. Helena Central Elementary School in Greensburg, La. In one experiment, the youth observed what happened when a fizzy antacid tablet was dropped into water.
They learned the tablet reacts in water by fizzing and foaming until the tablet is gone. Essentially, carbon dioxide gas is produced in this reaction. The students noticed the tablet reacted very slowly in the cold water, quite a bit faster in the hot water, and much, much faster when the tablet was crushed.
The students stated that in hot water the molecules are moving around very fast compared to the cold water. Since they are moving around very fast, more molecules are able to bump into the tablet in hot water than in cold water. Every bump of a water molecule causes a reaction to occur. So, if the molecules are bumping into the tablet more frequently, the tablet will dissolve quicker.