Physics Honors/AP 1 and 2

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Thermal Expansion

# Thermal Expansion

##### Materials
• Glass canning jar, including metal ring and jar seal
• Table of thermal expansion temperatures
##### Procedure
1. Assuming glass jar and metal ring are "sealed", estimate expansion required to loosen jar ring. Estimate temperature change required to achieve expansion if starting temperature is near freezing.
2. Fill jar 3/4 full of water; leave room for ice to expand. Estimate volume of air above water level.
3. Seal jar and place in refrigerator or freezer long enough to cool jar and contents by at least 20 °C. [CAUTION: if placing jar in freezer, do not leave longer that 20 minutes without checking. Remove jar when ice begins to form within jar contents.]
4. Test that jar seal is secure.
5. Using thermometer in contact with glass, then metal, measure glass and metal temperatures.
6. Measure a volume of water sufficient to immerse entire jar, and bring the bath water to approximately the target temperature estimated by your initial calculations. Place jar in water bath and allow it to achieve equilibrium (temperature will be below your estimated temperature!).
7. Attempt to loosen jar lid.
8. Create a source of hot water and add a measured amount of water no more than 25% of existing bath. Allow system to come to equilibrium, record temperature, and test whether you are able to loosen jar.
9. Repeat, slowly increasing temperature of water bath and jar and testing lid tightness. At what temperature are you able to loosen the lid?
10. Determine the linear thermal expansion of the metal jar lid ring due to the temperature change.
11. Using the temperature change, estimate partial pressure of water inside jar. How does this partial pressure affect yor ability to open the jar?

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