Erik Hartley
Dr. Phillip Murry
ES 210
UNDERSTANDING HOT SPRINGS
(CONVECTION)
Required Materials:
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4 Mason Jars
Water (Hot&Cold)
Food coloring (Red&Blue)
2 Index Cards
A location permitted to get wet
Pre-experiment Explanation:
Explain that a Hot Spring (like those found in Arkansas and Yellowstone National Park), are
pools of water that are heated to very high temperatures by the earth’s mantle. The cool water
runs deep inside the earth’s crust and the deeper the water travels, the warmer it becomes and it
rises up. Sometimes the water is pressurized to the point where it blasts upward in a high
velocity from the earth’s surface, this is called a geyser.
Procedure:
1. Take 2 jars and drop 2-4 drops of blue food coloring and add cold water to the brim of the jar.
2. Take 2 jars and drop 2-4 drops of red food coloring and add hot water to the brim of the jar.
3. Place an index card over the top of the red jar; this will create a seal, secure the card with
your hand as you quickly flip the jar over (upside-down) and position it over the open blue jar.
4. Line up the red jar directly over the blue jar, be sure the rim of the jars match perfectly.
5. Use both hands to secure the jars in place and have someone carefully remove the index
card. Note: do not let the jars move as this is done.
6. Now repeat the steps of experiment with the remaining two jars and the second index card.
EXCEPT this time place the blue jar on top instead of the red.
Observations and Discussion Points:
Erik Hartley
Dr. Phillip Murry
ES 210
 When you first placed the red jar over the blue jar, the colors stayed separated.
 Then when the blue jar was on top, the colors quickly mixed.
 Why do you think this happened?
Conclusion:
Why did this happen? Basically cold water is heavier than hot water. When water is hot, the
molecules rapidly move apart. In cold water, the molecules are tightly compacted. When the jars
are the same size, there is more space for the cold molecules to fit inside the hot water. The
cold water has a higher density opposed to the hot, so when the jar of hot water was positioned
under the jar of cold water, the hot water rises upwards as the cold drops downward (mixing).
When the jar of hot water sat above the cold water, there was zero movement because the hot
water was already sitting above the cold water.
Similar Lab Demonstration:
 Suspend a spiral cut piece of paper above a table lamp.
 Boil a pot of water.