What happens to gases as they are heated and cooled?
Materials needed
- Narrow necked jar with one whole stopper
- Balloon stick (available from cart or party supply stores)
- water
Procedure
1. Put a small amount of water in the bottom of the jar.
2. Insert the plastic tube through the stopper
3. Place the stopper in the jar. The lower and of the tube must be in the water.
4. Notice the water level in the tube.
5. Place the jar in a window in direct sunlight.
6. Check the water level in the tube every three or four minutes for at least one half hour.
7. What happened to the water level as the air warmed in the sunlight? Why?
8. Remove the jar from the sunlight and place it in cool place.
9. Again check the water level in the tube every few minutes.
10. What happened to the water level as the air cooled? Why?
11. What can you say about the effect of temperature change on gases?
2. Insert the plastic tube through the stopper
3. Place the stopper in the jar. The lower and of the tube must be in the water.
4. Notice the water level in the tube.
5. Place the jar in a window in direct sunlight.
6. Check the water level in the tube every three or four minutes for at least one half hour.
7. What happened to the water level as the air warmed in the sunlight? Why?
8. Remove the jar from the sunlight and place it in cool place.
9. Again check the water level in the tube every few minutes.
10. What happened to the water level as the air cooled? Why?
11. What can you say about the effect of temperature change on gases?
For the problems solvers:
blow up a balloon and measure the distance around it with a string. Mark the string to show the length required to reach around the balloon. Place the balloon over heat vent in front of a heater for a few minutes. Use the same string to measure the distance around the balloon again. Is there a difference? Can you explain why?
Learn what you can about hot balloons. Why do they rise into the air? Why do they come down again? Do balloon pilots usually fly their ships in the cool air of morning or in the heat of the afternoon? Why?
Learn what you can about hot balloons. Why do they rise into the air? Why do they come down again? Do balloon pilots usually fly their ships in the cool air of morning or in the heat of the afternoon? Why?
Teacher Information
This activity is very similar to activity 2.11, but this time the changes in water level in the tube are caused by expansion and contraction of air within the jar instead of expansion and contraction of liquid. As the air in the jar warms in the sunlight, it will expand, forcing water up the tube and very likely spilling it out the top of the tube, demonstrating that as the temperature of gas increases, the gas expands. At the air cools, it will contract and the level of the water in the tube will drop.
If food coloring is available, add a few drops to the water to make the water level in the tube more visible. This is a type of thermometer.
If food coloring is available, add a few drops to the water to make the water level in the tube more visible. This is a type of thermometer.
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