What is ash made of?

[OilIsMastery]

Back to the OP, according to volcanologist John Westgate from the University of Toronto, all ash has a unique chemical signature.

Westgate is a quaternary tephrochronologist, in plain English, a volcano detective. Westgate can identify a volcano anywhere in the world, using just one critical piece of evidence, volcanic ash.

Give Westgate some volcanic ash, and he'll track down the volcano that produced it.

JOHN WESTGATE (University of Toronto): We try to find out where the ash comes from, its parent volcano. And in that framework it's exactly like a DNA signature.

NARRATOR: Volcanic ash from every eruption is unique. It has a specific mixture of rock fragments and minerals that can point to its source.

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[Stryder]

Isn't that funny? That's exactly why people think we are "carbon based" even though we are actually hydrogen and oxygen (H2O) based.

Actually I think you find it's because we are "Carbon Based". If you were to look at CH₄ (not saying we are comprised wholey of that) the Hydrogen only has one bond so technically it's the Carbon that's the main element even though it's "outnumbered". Technically I doubt anything would ever be classed as "Hydrogen Base" other than of course "Hydrogen".

This is also the reason we can not be H₂O based, because you are attempting to base our foundations round an already formulated molecule. (The Molecule can't be Base in this instance)

[Billy T]

Quick skim indicates no one has yet mentioned that wood or coal fires in homes fireplaces leave unseen residues in the chimney also. They condense out of the hot flue gases and occasionally catch fire. (Can make deep roaring sound when they do as the chimney helps it "organ pipe".) Sometimes, especially with cracked chimney, this burns down houses. Most would not think of these deposits as ash, unless ash is defined as the material left behind by wood or coal fires.

[Fernan]

You guys look like 8 yr. old kids arguing about meaningless stuff.

But ash is the leftovers from that which burns, so what other stuff doesn't burn? Is it possible to burn away all the ash?

Yes, it is possible.

Every element has a boiling point beyond which it will evaporate for Carbon it is 4827 degrees C. The element with the highest boiling point is Tungsten at 5660 degrees C.

If you define "to burn" as "to undergo combustion" (i see that you need to choose your words very carefully in this forum) then you will need a compound with enough fuel and enough Oxygen to produce the right amount of heat for long enough to evaporate everything that won't combust.

If you use a broader definition of "to burn" then all you need to do is heat the compound and/or reduce it's pressure enough for it to evaporate. As mentioned above anthing will evaporate beyond 5660 degrees C at atmosphere pressure.

It's also worth mentioning that Carbon's melting point is the 3500 degrees C and it's the highest melting point of all known elements, so if you heat ashes beyond this point (as long as they're high in Carbon) it will turn into a crystal clear liquid, all the impurities will sink to the bottom and if you let it cool under enough pressure you get a diamond.

Is ash present when burning other things than organical stuff?

Yes, whenever you combust a compound containing some fuel and other elements ( not necessarily Carbon ), and the fuel does not produce enough heat to evaporate everything else you'll get some leftovers that are by your definition ashes.

The reason why ash is associated with organic compounds is because as mentioned above, Carbon has the heighest melting point so whenever you burn something organic almost everything else is going to either melt or evaporate.

[Captain Kremmen]

It is mainly made from metal oxides, which have a high boiling point, and would not be driven off in fires of normal heat.


Calcium Oxide white, has a boiling point of 2850C
Sodium Oxide, white, has a boiling point of 1950C
Magnesium Oxide, white, has a boiling point of 3600C

Potassium Oxide, yellowish white, decomposes at >350 so is probably burned off.
So will the oxides of nitrogen, sulphur, and phosphorous.

There are other metals in small quantities as well.

People used to make ash into soap by boiling it up in water with fat.

[Captain Kremmen]

Ash from a cremation oven, 760° to 1150°C (1400° to 2100°F), during the cremation process, will have few contaminants, and should be whiter.
Get down your granny's urn from the sideboard and check would you?

Sorry Gran, I'm just checking you for carbon remains. Won't be a jiff.

[Facial]

It is mainly made from metal oxides, which have a high boiling point, and would not be driven off in fires of normal heat.


Calcium Oxide white, has a boiling point of 2850C
Sodium Oxide, white, has a boiling point of 1950C
Magnesium Oxide, white, has a boiling point of 3600C

Potassium Oxide, yellowish white, decomposes at >350 so is probably burned off.
So will the oxides of nitrogen, sulphur, and phosphorous.

There are other metals in small quantities as well.

People used to make ash into soap by boiling it up in water with fat.

Finally, back on topic.

Nitrogen oxides are always in gaseous form, so they probably aren't a part of ash. The three main nutrients for plants, abbreviated "NPK" - nitrogen, phosphorus, and potassium - happen to be their main constituents after the three main elements of life - H,O,C.

Potassium oxide is formed in potash, but quickly forms into potassium hydroxide once the heat is reduced.
Phosphorus oxide is present too, but also absorbs water and turns into something else.
Magnesium oxide, derived from chlorophyll, would be fairly stable, turning into MgOH over a longer period of time.

[Cyperium]

Thank you for all your replies, this is a old thread and is yet at the first page after all this time! Never expected it to grow this large , shows that it was a good question though!

[ericdaniels]

i think those 2 nerdy guys should have a fight or keep arguing. it was kinda entertaining.

[Gremmie]

i think those 2 nerdy guys should have a fight or keep arguing. it was kinda entertaining.

They were just making ashes of themselves...

Of course that was a long time ago.

[WangLP]

I also want to know the answer...