PHYS320 Lab 21 Thermodynamics
Experiment 1: Can Crusher
1. According to Charles’ Law, what should happen to the volume of the gas in the can when you decrease the temperature?
2. According to Gay-Lussac’s law, what should happen to the pressure of the gas in the can as you decrease the temperature?
3. Knowing these two principles together, describe the pressure inside the can compared to the outside air after you placed it in the ice water.
4. What force caused the can to crush?
5. Why was it important for you to invert the can as you placed it in the ice water? (Hint: think about what would happen differently if the gas was allowed to escape the can, like the steam you saw in step 3.)
Experiment 2: Charles’s Law Experiment
1. What happened to the volume of gas when the syringe was submerged in each water bath? Using the concepts discussed above, describe why this occurs, keeping in mind the definition of temperature.
2. Using a ruler, draw a straight line of best fit through your data points, extrapolating the line until it intersects the (negative) x-axis. Why can you assume a straight line, i.e., a linear relationship?
3. At what temperature does your line intersect the x-axis? What volume corresponds to this temperature?
4.Do you think it would be possible to cool a real gas down to zero volume? What do you think would happen first?
5. Is your measurement of absolute zero close to the actual value (-273 °C)? How might you change the experiment to get closer to the actual value?
6. When does the air in the syringe do work? When is work being done on the air inside?
Experiment 3: Entropy Simulation
1. How did the arrangement of pennies change after each shake? Did you get different results based on how many pennies were in the box? Did you ever end with an equal arrangement of heads and tails?
2.After starting with an “ordered” set in step 4, how likely do you think it is to arrive back in a state of “order” after shaking the box numerous times (i.e., end with all heads or all tails)? How do you think this compares to the probability of landing on all heads or tails with only two or four pennies
3.How does this help demonstrate the property of irreversibility in thermal processes (think of the pennies as gas particles in a chamber)?
4.How does this experiment demonstrate a natural progression from an ordered system to a disordered system?
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