trip96 - 5-9-2012 at 12:57
Hey everyone! I heat my house in winter via a wood burning stove. As you can imagine I end up with garbage pales worth of ash at the end of it.
What usefull reagents could I make using ash?
Let's build a list!
marko - 5-9-2012 at 13:07
Mostly NaOH, KOH. I suppose much of it would turn to carbonate. I think it depends on the type of wood - most is higher in K. (hence "potash"...
pot... ash... from which we get 'potassium').
In the old days you'd leech the lye from the ash with water, and use it to make soap.
I'd imagine there is some other mineral content, but much lower quantity.
elementcollector1 - 5-9-2012 at 13:42
I still don't understand how KOH results from the burning of wood. I always assumed they meant you had to treat the K2CO3 with Ca(OH)2, and that would
form your KOH.
EDIT: Incidentally, is common gravel made of calcium hydroxide? Every lye page I go to says to filter the boiled carbonate or whatever through gravel
to obtain lye.
[Edited on 5-9-2012 by elementcollector1]
Poppy - 5-9-2012 at 13:48
You can find everything from gold to uranium. Its just in minimal proportions. It's true. Just figure out how the elements have been throughly
dispersed in soil. Mercury is by most a rare element in ash, some of its compounds have a minuscle solubility product. Plants probabily would not take
any chance to suck a few atoms of this.
[Edited on 9-5-2012 by Poppy]
bbartlog - 5-9-2012 at 17:22
Most of the ash is actually CaCO3 (but there is also MgCO3 and some silica compounds). But the stuff you can dissolve out is mostly K2CO3. There is
some KOH (the hotter the fire, the more KOH), but it tends to turn into K2CO3 if you leach it out with water and boil the resulting solution down, as
atmospheric CO2 is absorbed.
K2SO4 and small amounts of KCl can also be obtained if you perform fractional crystallization on the ley.
SM2 - 6-9-2012 at 05:30
POTASH, "Pot-Ash" - Potassium. Yep, the water soluble portion is mostly potassium carbonate, and if your lucky, you can even filter through activated
charcoal.
An interesting thing to do, is wrap a small amount of solid Lye into a sheet of Al foil. Wind it up to make a nice turd. Then place it in a nice oak
fire. The Na formed will make quite a little show.
Poppy - 6-9-2012 at 09:03
What sodium o0?
Elemental sodium??????
Vargouille - 6-9-2012 at 10:28
At elevated temperatures there should be a small amount of the sodium formed, which reacts with moisture in the air immediately due to the heat,
reforming sodium hydroxide, and the cycle continues until the aluminum is used up. It may even be to such a small degree that the flame is almost
indistinguishable from a sodium salt burning at high temperatures. I'm searching for a formula, or several, to test this, but it may take some time.
EDIT: As predicted, but not quantified, by the Nerst Equation, adapted from its typical use as a wet electrochemical equation. Here, Eo is -1.05V, T is a large, unknown quantity, z
is 3 e-, and (ln Q) is a negative value, meaning that the amount of product is less than the amount of reactants at a particular point.
With a very small amount of sodium formed and a very high temperature, E>0, such that the reaction proceeds. Unless, of course, I am ignoring some
other part of the physics behind the chemistry.
[Edited on 6-9-2012 by Vargouille]
Poppy - 6-9-2012 at 13:06
Not sure Na is a strong base Al is amphoteric, probably some alumixodide would form
vmelkon - 10-9-2012 at 05:05
I don't think you can make sodium with NaOH+ Al. I have heated Draino with a torch. It fizzes and forms a rock hard solid that looks like salt. It
produces sodium aluminate.
elementcollector1 - 10-9-2012 at 19:07
So, how does one recover pure KOH from this ashy mess? If I boil it down, it'll just absorb CO2 again. I can't evaporate it because KOH is too
hydroscopic.
platedish29 - 10-9-2012 at 21:13
Once I collected ashes from a large pile, mixed with water, filtered and neutralised with nitric acid. I was not aware calcium compounds had been
filtered.
Then boiled and finally dried over an aluminium plate. I could even make black powder out of it!
Take this. Enjoy!
[Edited on 11-9-2012 by platedish29]
Attachment: misra93a.pdf (276kB)
This file has been downloaded 529 times