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Lastweek we learned the way pressure, volumeand temperaturecontrol the
behavior of gases. In particular, you know the equation of state for an ideal gas and
understand the conditions for which the behavior of any common gas can be
approximately described as ideal. Today we will experiment with a useful
application of changes in volume, temperature and pressure in a gas: the heat
engine.
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Equipment:
Heat Engine apparatus that includes:
Base: cylinder, piston and platform
Hose with one-way check valves
Air chamber with one holed rubber stopper
Termometers
Hot water bath
Cold water bath
100 g and 200 g masses
(1) Equipment Set-up:
* The hot water bath should be at around 70ºC.
* The cold water bath can be cold tap water, the colder the better. Add ice, if
available.
* Connect the tubing to the rubber stopper and also to a connecting port in the
base assembly. Do not put the rubber stopper into the air chamber yet.
* Close the other connecting port. Make sure it is well closed, or the system
will leak air. Move the piston up and down and check that no air is escaping from
the closed valve. If it is, then you need to secure it tighter.
* Place the piston on the 20 mm mark and, while manually keeping it there,
put the rubber stopper in the air chamber and secure it tightly.
Procedure: the different stages of the cycle will be indentified as POINT A, B, C, and
D. Before you do anything with the heat engine, each step of the cycle will be
described below. You are asked to make predictionsand anwer a few questions
before doing to the actual experiment. Look at the picture of the cycles for reference.
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