Hand Boiler by Anna Mkrtchyan
Author
Anna Mkrtchyan, AGBU Manoogian-Demirdjian School
Principles
Hand boilers demonstrate Charles’s Law and vapor-liquid equilibrium.
Standards
California State Standard in Chemistry 4.c The student knows how to apply the gas laws
to relations between the pressure, temperature, and volume of any amount of an ideal gas
or any mixture of ideal gases. A sample of relevant national and state science education
standards: Heating and cooling cause changes in the properties of matter. Atoms and molecules
are perpetually in motion. Increased temperature means greater average energy of motion, so
most substances expand when heated. Students know how to apply the gas laws to relations
between the pressure, temperature, and volume of any amount of an ideal gas or any mixture of
ideal gases.
Materials needed
Hand boiler
Procedure
Hand Boilers are looped and twisted glass sculptures containing a liquid that will "boil" as heat is transferred from your bare hand. Simply hold the large bulb end in the palm of your hand and within minutes, your body heat will cause the liquid to rise.
Explanation
The colored liquid in the boiler is comprised of a volatile mixture of liquids that have a boiling point just above room temperature. The body heat from your hand causes the liquid to boil, which in turn makes the liquid evaporate, turning it to gas.
The colored fluid in the bottom bulb is ethyl alcohol, a chemical with a low boiling point, or the temperature at which it boils. In fact, that boiling point is closer to body temperature. The body heat from your hand causes the liquid to boil, which in turn makes the liquid evaporate, turning it to gas.We see that, as the fluid heats up, it evaporates and tries to expand, but it has nowhere to go but up into this twisty loopty-loop of glass. It flows upwards into the top bulb where it appears to bubble and boil. The expanding gas pushes the liquid upwards and when you release your hand, equilibrium is re-established. The gas condenses into a liquid again and flows back into the lower bulb.
ACTIVITIES:
Have the students hold the boiler upright by the larger bulb. How long does it take for the liquid to “boil”? Is there a student in class whose hand does not make it “boil”? Take the temperature of the students’ hands. Notice the difference. How do you make the liquid go down again? Hold onto the top bulb only. What happens if you hold both bulbs? Why? Can you make the liquid move by using cooling instead of heating? Try putting ice on the bulbs and see what happens. After several uses, the boiler won’t work for a while. Why not? Will the boiler work if upside down? Why not?
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