Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Maybe redundant topic, but is fire plasma ?
metalresearcher
International Hazard
*****




Posts: 614
Registered: 7-9-2010
Member Is Offline

Mood: Reactive

[*] posted on 24-1-2021 at 03:48
Maybe redundant topic, but is fire plasma ?


Some say NO, some YES.

Here a discussion on stackoverflow:
https://physics.stackexchange.com/questions/23469/is-fire-pl...

I say :
NO, because the temperature is too low, it is a pure chemical process.
YES, because when salts are in the fire, its spectrum shows emission lines, e.g. the bright yellow Na-D line. When putting copper salts or even metallic Cu in the fire, flames will be colored green-blue.

What do you think ?
View user's profile View All Posts By User
unionised
International Hazard
*****




Posts: 4626
Registered: 1-11-2003
Location: UK
Member Is Offline

Mood: No Mood

[*] posted on 24-1-2021 at 04:23


Since you can pass an electrical current through a flame, there's no way to dispute the fact that it's ionised, so it's a plasma.
On the other hand, it's a weak plasma- the degree of ionisation is low.

The yellow colour from sodium in a flame is due to neutral sodium atoms, rather than ions.
View user's profile View All Posts By User
Antiswat
International Hazard
*****




Posts: 1341
Registered: 12-12-2012
Location: Dysrope (aka europe)
Member Is Offline

Mood: dangerously practical

[*] posted on 28-1-2021 at 02:53


low density plasma, lets settle at that shall we. never really bothered to puzzle this one into place but i always knew fire and plasma was somehow related




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
View user's profile View All Posts By User
unionised
International Hazard
*****




Posts: 4626
Registered: 1-11-2003
Location: UK
Member Is Offline

Mood: No Mood

[*] posted on 28-1-2021 at 04:49


Quote: Originally posted by Antiswat  
low density plasma, lets settle at that shall we.

Why?
The density is a lot higher than that in a neon sign, for example.
View user's profile View All Posts By User
Fulmen
International Hazard
*****




Posts: 1465
Registered: 24-9-2005
Member Is Offline

Mood: Bored

[*] posted on 28-1-2021 at 08:05


Quote: Originally posted by unionised  
it's ionised, so it's a plasma


There might be ionized atoms in a flame, but calling that plasma is like calling air for helium.




We're not banging rocks together here. We know how to put a man back together.
View user's profile View All Posts By User
rockyit98
National Hazard
****




Posts: 261
Registered: 12-4-2019
Location: The Known Universe
Member Is Offline

Mood: no mood is a good mood

[*] posted on 28-1-2021 at 08:21


Nope! think of it as sea water. got some ions but mostly covalent molecules .and some free radicals here and there.



"A mind is a terrible thing to lose"-Meisner
View user's profile View All Posts By User
clearly_not_atara
International Hazard
*****




Posts: 2141
Registered: 3-11-2013
Member Is Offline

Mood: Big

[*] posted on 28-1-2021 at 08:30


Instead of looking at specific questions like "is fire plasma?", physics as a discipline focuses on answers to questions like "how do I determine if a sample is a plasma or a gas?". You will find a more orderly discussion here:

https://physics.stackexchange.com/questions/83658/is-there-a...

http://scienceline.ucsb.edu/getkey.php?key=3257

" A gas has zero conductivity, but when it turns into a plasma, its conductivity steadily grows but doesn't jump."

This is a little misleading: usually there is a point at which one of the derivatives of conductivity with respect to temperature, that is: (d/dT)^n [S(T)] shows a singularity for some n. Also, sometimes plasmas do have a first-order phase transition, but it tends to be past the point at which they start to ionized (the weakly-ionized to strongly-ionized first-order transition).

For a particular source you're interested in, the only way to know is to set it on fire and get a couple of electrodes and an ammeter :D

The best example plasma for teaching is probably a glow discharge, because a: it is relatively common and b: it emphasizes the key measurable property of plasma (conductivity)

https://en.wikipedia.org/wiki/Glow_discharge

[Edited on 28-1-2021 by clearly_not_atara]




[Edited on 04-20-1969 by clearly_not_atara]
View user's profile View All Posts By User
metalresearcher
International Hazard
*****




Posts: 614
Registered: 7-9-2010
Member Is Offline

Mood: Reactive

[*] posted on 28-1-2021 at 10:00


Glow discharge, is that not the same as a Corona discharge, appearing at high voltage power lines ?
In that case, the air close to the high voltage conductors, where the corona appears is also a plasma ?
View user's profile View All Posts By User
clearly_not_atara
International Hazard
*****




Posts: 2141
Registered: 3-11-2013
Member Is Offline

Mood: Big

[*] posted on 28-1-2021 at 10:09


Yes, that is definitely a plasma.



[Edited on 04-20-1969 by clearly_not_atara]
View user's profile View All Posts By User
macckone
International Hazard
*****




Posts: 1778
Registered: 1-3-2013
Location: Over a mile high
Member Is Offline

Mood: Electrical

[*] posted on 28-1-2021 at 16:38


It is partially ionized gas, aka plasma.
It isn't pure plasma, like in a sustained electric arc.
It is like asking if a slushy is a liquid or a solid.
Another example is fog or clouds, is it a liquid or a gas, in this case it is a suspension.
There should probably have its own name, I don't know ... like ... partially ionized gas.
View user's profile View All Posts By User
Morgan
International Hazard
*****




Posts: 1508
Registered: 28-12-2010
Member Is Offline

Mood: No Mood

[*] posted on 28-1-2021 at 16:51


Tidbit
"St. Elmo's fire is a weather phenomenon in which luminous plasma is created by a corona discharge from a sharp or pointed object in a strong electric field in the atmosphere (such as those generated by thunderstorms or created by a volcanic eruption)."
https://en.wikipedia.org/wiki/St._Elmo%27s_fire
View user's profile View All Posts By User

  Go To Top