Measuring the conductance of flames

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    Conductance Measuring
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Discussion Overview

The discussion centers around measuring the conductance of flames, specifically in relation to an experiment involving burning salts of various elements and measuring the conductance across nichrome electrodes. Participants explore the underlying physics, including potential connections to ionization and the Boltzmann factor.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant expresses uncertainty about linking the Boltzmann factor to the conductance of flames and seeks further physics to support their theory.
  • Another participant questions whether the discussion is about electrical or thermal conductance and suggests that the mention of the Boltzmann constant may indicate a misunderstanding.
  • A participant shares experimental results showing varying conductance values for different elements and seeks to understand the physics behind the observed increase in conductance with the number of electrons in atomic shells.
  • One reply suggests considering the ionization state of the chemicals involved, proposing that larger molecules may have higher ionization states.
  • Another participant proposes a relationship between conductivity and ionization energy, suggesting a logarithmic plot for analysis while cautioning about the presence of chlorine in the salts used.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the underlying physics of flame conductance, with multiple competing views and questions remaining unresolved.

Contextual Notes

Participants express uncertainty regarding the connection between conductance and atomic structure, as well as the influence of ionization states. There are also mentions of potential experimental limitations, such as ensuring consistent burning rates of materials.

Conducto
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Hi, I'm doing a project on mesuring the conductance of flames, but I need a lot more physics to back up my theory. I'm pretty sure that the Boltzmann factor is involved, however I can't link the two items together.

The experiment so far has worked, by using a bunsen burner to burn the salts of elements, i.e. Barium Chloride, Calcium Chloride etc and measuring the conductance of the flame across a gap of 2mm between 2 nichrome electrodes.

Thanks in advance for any replies! :bugeye:
 
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Do you mean electrical conductance or thermal conductance? If you are talking about electrical conductance ("conductivity"), as I think you are, your mention of the Boltzmann constant indicates that you are up the wrong tree.

Your experiment indicates a rather interesting idea and I urge you to continue. To obtain meaningful data you will need: a multimeter that measures voltage, current and resistance; a variable voltage source (0 to 12 V DC would be good); a physics texbook with four or five chapters on electricity and circuits.

Do not mess with voltages higher than 12 volts, and keep your skin dry. Watch "Leathal Weapon 2" to see why.
 
Thanks for the reply,

I have already conducted the experiment with reasonable success, but what I really need is some physics to relate the reason behind the following results:

Sodium 1.23
Calcium 1.37
Strontium 1.50
Potassium 2.18
Barium 1.66

(values are measured in Conductance (µS))

What I really need to know is the physics behind what makes this work, and why the conductance increases with the number of electrons in the atoms shells. Is there any formula/theories which relate to this?
 
I can't give you any patent answers, but think you will have to consider the ionization state of the various chemials. Perhaps the larger molecules have a tendency to higher states of ionization??


Many years ago I read of something called a Flame speaker. To make one all you would need do is place an audio signal on your needles. The audio signal will cause oscilations in the flame which will act a nearly perfect speaker. Have always wanted to try it.
 
Are you expecting conductivity to go like
exp(-ionization energy/k_B*T)

I'd suggest you first make sure you're burning materials at the same rate.
then try plotting on log scale "might" get a straight line.
(but don't forget the Cl that's also in the salt!) - Good Luck -
 

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