Hot Water Convection

This experiment is designed illustrate how hot springs work and where the hot water is coming from.It shows hot water convection very well to the students . Because hot water is being used and to prevent accidents, an adult should always be assisting. (Adult supervision recommended.)

Supplies You Will Need:

4 identical, clear, jars
Hot water
Cold water
Blue dye or food coloring
Red dye or food coloring
Two index cards (large enough to cover the mouth of the jars)
An area that is okay to get wet


Take all of your materials to the area that is ok to get wet.
Using cold water from the sink fill two of the jars to the top with cold water. Put blue food coloring into both jars and then slowly add more water until it “bulges” around the rim of the jars.
Fill the next two jars with hot water from the sink. Put red food coloring in these two jars and slowly add more water to for the bulge as with the blue jar.
Place the index card on top of one of your red jars, then quickly turn the jar over while holding the index card in place. This should form a seal preventing the water from leaking out.
Place the upside down jar on top of a blue jar, make sure the mouths of the jar line up perfectly. Then slowly remove the index card from between the two.
Complete the same process only with the blue jar on top and the red beneath it. Take notice of the difference in the reactions of the water in both sets of jars.

What You Will See:

With the red jar on top you should notice that the colored water remains separated, very little blending of the two will occur.

With the other jar you should notice that the blue water will sink forcing the red water into the top jar. This is because cold water is “heavier” than hot water and is a good illustration of hot water convection.

This is the same process that happens in hot springs. As the water at the surface cools it flows down into cavities beneath the springs that are filled with hot water. This causes the hot water to be forced to the surface, and results in a self-cycling process that keeps the spring hot at all times.

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