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I'm trying to get a head start on our lab experiment next week about Boyle's Law.

The set-up is we have an air chamber can immersed in a pot of boiling water (which is kept boiling over an electric stove). This air chamber can is attached to some kind of apparatus that allows you to vary the pressure inside the chamber can using masses of different weights. So, after immersion in the water, the piston inside the can is then lifted to its max height. The pressure inside is then varied by adding the masses. The pressure is measured using a gas pressure sensor.

My question is, this experiment being a test of Boyle's Law, how is the temperature kept constant throughout the experiment when it is performed over an electric stove all the time? I mean, I guess we could attach a thermometer beside the can but that will just give us the temp reading. Or maybe it's as simple as turning off the stove when the temp reading gets too high? But I was hoping you guys might know an intelligent way on how to ensure that the temperature is kept constant at all times.

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The boiling water will boil at a constant temperature. As long as the can is in the boiling water, you will not need to worry about the temperature of the stove.

If this experiment is run at sea level, and you are using pure water, the can will remain at 100 deg C throughout the experiment. If you are at an elevation higher than sea level, and you want to know the actual boiling temperature, you will need to correct your boiling temperature for a lower atmospheric pressure (you could interpolate from a steam table, knowing the atmospheric pressure at your location), or you could just measure the boiling water's temperature with a thermometer.

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  • $\begingroup$ I believe there's also the issue of heat being conducted through the cooking pot directly to the air chamber, which could heat the air inside the chamber beyond the boiling point of the surrounding water. You might specify that your answer concerns a chamber heated only by the water. $\endgroup$ – Asher Oct 12 '15 at 10:17

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