Non-Messy Heat Bath Solutions for Physics Lab Experiments

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In summary, Ben has been thinking of ways to make the lab more convenient and safer for the students. He's been considering using a sand bath or a heating mantle, but he's not sure if either of those solutions are accurate enough. He's also been considering using a thermocouple to measure the temperature.
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bcrowell
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I teach physics at a community college, and I do a lab in which the students measure the pressure of air at constant volume, extrapolating to determine absolute zero. To get the best results (and also to make the lab more fun), I've worked on getting the widest possible range of temperatures. Currently we're using mineral oil for the hottest temp (smoke point of about 150 C) and an acetone/dry ice slurry for the coldest (about -20 C). The mineral oil has some disadvantages, however. It's messy, it isn't reusable, and if we don't dry out the glassware before heating it, we get spattering. Sometimes students are inattentive about the temp and it starts to smoke. I've been trying to figure out of there is some other solution that would be more convenient.

What might be nice would be some kind of soft, sealed, reusable thermal pack. Some of these are sold for use with food, others for medical use. They seem to contain cross-linked polymers. Handling them would probably be safer than handling the mineral oil. I'm not sure, however, how hot you can get these things. One brand is advertised as being autoclavable at 120 C, which isn't that hot. I'm also not sure if you could really mold them around the Erlenmeyer flask holding the air sample.

Another idea that's occurred to me is simply to put some canola oil in a ziplock bag and heat it in a microwave. The smoke point of canola oil is 225 C, which is quite a bit higher than the 150 C that I'm shooting for. In the worst case where the bag inflated and popped open during heating, we'd just get a mess inside the microwave.

Any suggestions? Thanks in advance!

-Ben
 
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  • #2
Is it possible to use a simple sand bath (http://en.wikipedia.org/wiki/Sand_bath)?

I'm not sure heating canola oil in a ziplock is the best solution. I'm not so sure the ziplock be able to withstand the high temperatures and be secure enough to prevent spilling hot oil on your students.
 
  • #3
Aha! Thanks, Ygggdrasil, that's exactly the information I needed!

[EDIT] The only thing that occurs to me now is that I'm not sure how equalized the temperature of the sand would be. You probably can't stir it as well as you can stir a liquid.
 
  • #4
Heating mantle?
 
  • #6
Use a thermocouple within the air volume. Simplest way is to buy a 1/16" dia. SS probe type TC (say from Omega) and use a swagelok or similar fitting to handle the pressure. Some method of stirring the air within would be best, say a modified magnetic stirrer?
 

1. What are non-messy heat bath solutions?

Non-messy heat bath solutions are substances that are used in physics lab experiments to maintain a consistent temperature for the materials being tested. They are typically liquids and are designed to be mess-free, meaning they are easy to handle and do not create any spills or stains.

2. How are non-messy heat bath solutions different from traditional heat baths?

Traditional heat baths usually involve using water or oil as the heating medium, which can be messy and difficult to control. Non-messy heat bath solutions, on the other hand, are specifically formulated to be easy to handle and to maintain a stable temperature without creating any mess.

3. What types of non-messy heat bath solutions are commonly used in physics lab experiments?

Some commonly used non-messy heat bath solutions include silicone oils, glycol-water mixtures, and thermostatic fluids. These substances have high boiling points and are able to maintain a consistent temperature, making them ideal for use in heat baths.

4. How do non-messy heat bath solutions work?

Non-messy heat bath solutions work by absorbing and distributing heat evenly throughout the substance. This helps to maintain a constant temperature for the materials being tested. They also have a high specific heat capacity, meaning they can absorb a lot of heat without a significant change in temperature.

5. Are non-messy heat bath solutions safe to use in experiments?

Yes, non-messy heat bath solutions are generally safe to use in physics lab experiments. However, it is important to follow all safety precautions and instructions provided by the manufacturer. Some solutions may have specific handling or disposal guidelines, so it is important to read the labels carefully before use.

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