Finding Absolute Zero Experimentally: Investigating a Capillary Tube

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Discussion Overview

The discussion centers around an experimental approach to determining the temperature of absolute zero using a capillary tube filled with oil. Participants explore the methodology, results, and potential sources of error in the experiment, which involves heating the tube and measuring the gas length at various temperatures.

Discussion Character

  • Experimental/applied
  • Debate/contested

Main Points Raised

  • One participant describes an experiment where a capillary tube is heated, and the resulting gas length is measured at different temperatures, leading to a calculated c value around -150°C.
  • Another participant questions the accuracy of maintaining specific temperatures during the experiment, suggesting that it is challenging to hold gases at precise temperatures outside of certain controlled conditions.
  • Some participants express uncertainty about the experimental setup, including whether the same oil sample was used and the consistency of the measurements across trials.
  • One participant notes that while air is not an ideal gas, it can be approximated as such, which may affect the results.
  • Participants discuss the importance of ensuring that the gas temperature is accurately measured and suggest methods for achieving this, such as using baths of ice or boiling water for specific reference points.
  • Another participant mentions that despite variations in oil and conditions, the results across multiple tests were consistently around -150°C, indicating a possible systematic error.

Areas of Agreement / Disagreement

Participants express varying levels of agreement on the challenges of maintaining accurate temperatures and the implications for the experiment's results. There is no consensus on the source of the significant error observed in the c value, and multiple competing views on the experimental methodology remain.

Contextual Notes

Participants note limitations in the experimental setup, including potential issues with temperature control and the consistency of measurements. The discussion reflects uncertainty regarding the accuracy of the temperature readings and the implications for the calculated values.

miniradman
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We were presented with a task of calculating the temperature of absolute zero experimentally.

To do this, we were given a capillary tube with one end sealed. Then we heated the tube up in a bunsen burner and quickly put the open end in some cooking oil. The oil was sucked up as the gas within the tube cooled down. The result of this was that there was a small section of the tube filled with oil. (image of setup attatched)

Once we had out tube filled, we exposed them to 4 different temperatures (5oC, 25oC, 55oC and 90oC and measured (using a ruler) the length of the gas in between the oil and sealed end of the tube.

Once we had these points we graphed them to get a y=mx+c function. The only problem is that my c value (when the volume equals zero) is around -150oC. I've repeated the experiment 4 times with the same results and I don't know what is affecting the results so severly.

Any ideas would be greatly appreciated :biggrin:
 

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miniradman said:
calculating the temperature of absolute zero experimentally

Determining, not calculating. Or calculating from experimental results.

I've repeated the experiment 4 times with the same results and I don't know what is affecting the results so severly.

Same tube with same oil sample each time?

Can you show numbers you got?

I never did such an experiment, and I have no clever ideas about what went wrong. But I agree with you that the error seems way too large. While air is not an ideal gas, it can be approximated by one quite accurately.
 
Are you certain that the gas was at 5C, 25C, etc.? It is very difficult to hold something at a specific temperature like that. With 0C, you can put it into a bath of melting ice, or with 100C, boiling water- water will stay at those temperatures as long as there is still some ice or water left. One other temperature you can be sure of is "room temperature"- let the object sit for an extended period, then measure the temperature of the air. Water does not "stay" at other temperatures.
 
Borek said:
Determining, not calculating. Or calculating from experimental results.
sorry :smile:
Borek said:
Same tube with same oil sample each time?

Can you show numbers you got?

I never did such an experiment, and I have no clever ideas about what went wrong. But I agree with you that the error seems way too large. While air is not an ideal gas, it can be approximated by one quite accurately.
Well, I used identical capillary tubes but the amount of oil was in the same, not was it in the same place (its a little hard to get exact). But even when the oil wasn't the same for each test, the c values for the linear equation I got were very close to all tests.

err... I only have the results for the test I intended to use for my practical report. But I know for a fact that everyone in the class (all 2 of them) and the teacher had around -150 degrees celsius as well.

25oC = 3cm
52oC = 3.5cm
91oC = 4cm
10oC = 2.6cm

Are you certain that the gas was at 5C, 25C, etc.? It is very difficult to hold something at a specific temperature like that. With 0C, you can put it into a bath of melting ice, or with 100C, boiling water- water will stay at those temperatures as long as there is still some ice or water left. One other temperature you can be sure of is "room temperature"- let the object sit for an extended period, then measure the temperature of the air. Water does not "stay" at other temperatures.
T 11:39 AM
Well the capillary tube's wall was very very thin and I read the level of the oil while it was still in the water. So I assurmed that the temperatures would have equalized by the time I recorded the result. :smile:
 

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