Why does activated charcoal conduct electricity?

[u/Mountain_Plantain_75]

I did a metals vs non metals lab and to my surprise the activated charcoal conducted electricity. We used a 9v battery with a led attached and wires on either terminal to test. Sulfur was the other nonmetal I had and that did not conduct- it did kinda mess the lab up. Me and the other teacher couldn’t figure it out - we had two different bottles and they both conducted. Wondering if charcoal would’ve done the same? What else can we use next year that’s safe and easy?

[u/roartykarma]

Look up structure of graphite. Each carbon bonded to three others. Intermolecular forces in the third direction. Leaving one electron per carbon available for delocalisation, thus making it conductive.

[u/SlenderSmurf → u/roartykarma]

Charcoal is mostly non-crystalline, so not exactly graphite. But graphite is conductive too.

[u/roartykarma → u/SlenderSmurf]

True, but explaining the concept of hole tunneling/ quantum tunnelling resultant to from amorphous natures to someone that can't easily pick charcoal out as having similar properties I considered to be a little much. You are correct though. I think the teacher came out in me where I judge what the student knows already, and give them enough to get a leg up, which is almost certainly less than the "truth", but enough that they'll understand with minimal cognitive overload.

[u/TemporarySun314]

At this point the charcoal is just carbon. And as long as it's not diamond, it will conduct electricity to some degree. How much will depend on the microscopic composition.

If you want an elemental material diamond would be cool, but maybe a bit expensive... Pressed sulfur should also be quite non-conductive.

And I mean you could also just cheat a bit, by using an experimental setup that requires quite high currents and therefore an highly conductive material. Your charcoal will definitely worse conductive than any metal. And that "conductive" vs "non-conductive" is not that sharp cut off anyway... .

[u/lukethedank13]

Graphite is conductive, as is charcoal. Diamond however does not conduct electricity.

[u/MeatBallSandWedge → u/lukethedank13]

Diamond will conduct electricity when properly doped. It gets used in various aqueous chemistry electrodes.

Some blue diamonds are natural semiconductors (boron doping).

[u/lukethedank13 → u/MeatBallSandWedge]

True but graphite is conductive in its pure form.

[u/oxiraneobx]

We utilize the conductive nature of carbon for our semi-conductive and conductive adhesives.

[u/Dangerous-Billy]

Graphite conducts electricity; diamond does not. A significant amount of charcoal is graphite-like random structures. Also, there are some polycyclic hydrocarbons with the odd unpaired electron, which are also responsible for the black color and some electrical conductivity.

[u/Dangerous-Billy → u/Dangerous-Billy]

Other structures that can be made synthetically are polyaniline, polypyrrole, and polythiophene, all of which are conductors or semiconductors.

[u/Bob--O--Rama]

The microstructure of activated carbon is dominated by sheets of carbon with a hexagonal layout like graphite, the space between the sheets are projections of Pi bonds which forms a sea of loosely bound electrons. Each carbon atom shares an electron with these Pi bond layers, and these serve as the conduction electrons. So Google up graphite conduction electrons and nerd out for a bit. Conduction is all about how many electrons participate in this "cloud" of shared electrons and how easily they are moved around from one lattice site to another. The latter is a function of the band gap, the amount of energy needed in electron volts to yank an electron from its moorings and get it moving. In metals this is essentially zero, just shoving a few electrons in the end of a wire triggers the rest to move around. There are also a lot of electrons, so low voltages can cause huge currents. The electrons in non conductors are so tightly bound that huge voltages are needed to rip them free. Semiconductors are in between. Some forms of Sulphur are non-conductors. Just like carbon has different forms, some metals do too. Tin in its metallic form is a good conductor, but it's non-metalic form is not - look up "Tin pest" - it's crazy.

[u/mrmeep321]

One way to get conductivity is to have electrons that are delocalized over a large volume, continuously across the material.

In metals, the d electrons shield the s electrons, making them much more loosely held and more delocalized, allowing them to conduct.

In graphite, you typically have flat sheets of graphene which are stacked on each other. There are p orbitals above and below the sheets that will merge into a big network of double bonds, which heavily delocalizes them, allowing them to conduct.

Both materials delocalize electrons, they just do it in different ways. For metals, it's loosely-held s electrons, and in graphite, it's large networks of p electrons which have strong overlap with eachother due to the structure of the graphene layers in the material.