I’m not going to. sounds like a PITA.
Anyway, I looked it up and this site tells you how to make KOH (rather than NaOH)
You get rain water (soft water they say), you burn some wood (I think they said hard wood).
you cover the ashes with the water and then some time later you drain off the lye.
I don’t understand the chemical reaction.
whats happening here?

purple said:

I’m not going to. sounds like a PITA.
Anyway, I looked it up and this site tells you how to make KOH (rather than NaOH)
You get rain water (soft water they say), you burn some wood (I think they said hard wood).
you cover the ashes with the water and then some time later you drain off the lye.
I don’t understand the chemical reaction.
whats happening here?

Tap water and any wood should be fine.

2KOH + CO2 <=> K2CO3 + H2O

K2CO3

wheres this from?

purple said:

K2CO3

wheres this from?

its not apparent from the equation but if you bubble co2 through water it becomes carbonic acid

the acid reacts with the K to form a carbonate

wookiemeister said:

purple said:

K2CO3

wheres this from?

its not apparent from the equation but if you bubble co2 through water it becomes carbonic acid

the acid reacts with the K to form a carbonate

I’ve read that they used to find that the water down stream of wood being burnt, was good forwashing clothes in

the KOH makes grease turn into soap which then can be washed out

if you get some caustic soda (sodium hydroxide ) on ya hands it starts turning your hands into soap/ the grease on your hands. its known as saponification (sapon is French for soap)

I’ve generally assumed that the K was coming from the burnt wood ie the mineral K is some of the stuff left over and not affected by heat.

http://en.wikipedia.org/wiki/Saponification

I didn’t realise that lithium grease was actually a soap!

purple said:

K2CO3

wheres this from?

Plants need potassium and so they pull it out of the soil. I’m not a botanist, so don’t ask me what they do with it. :) But it’s almost always in fertilisers.

Anyway, when you burn the wood the organic compounds get broken down. The carbon & hydrogen content tend to get converted into elemental carbon (charcoal), carbon dioxide & water (in vapour form); the other stuff tends to get converted into elemental oxides. But potassium oxide is very reactive stuff. It’ll react with water to make potassium hydroxide. But it also has a strong affinity for carbon dioxide, reacting to form potassium carbonate.

So this thread has now gone like an hour without a Fight Club reference.

PM 2Ring said:

purple said:

K2CO3

wheres this from?

Plants need potassium and so they pull it out of the soil. I’m not a botanist, so don’t ask me what they do with it. :) But it’s almost always in fertilisers.

Anyway, when you burn the wood the organic compounds get broken down. The carbon & hydrogen content tend to get converted into elemental carbon (charcoal), carbon dioxide & water (in vapour form); the other stuff tends to get converted into elemental oxides. But potassium oxide is very reactive stuff. It’ll react with water to make potassium hydroxide. But it also has a strong affinity for carbon dioxide, reacting to form potassium carbonate.

so it will react with co2 in the absence of water?

• So this thread has now gone like an hour without a Fight Club reference.

Well, you know, the first rule and all…

wookiemeister said:

PM 2Ring said:

But potassium oxide is very reactive stuff. It’ll react with water to make potassium hydroxide. But it also has a strong affinity for carbon dioxide, reacting to form potassium carbonate.

so it will react with co2 in the absence of water?

Sure; but water isn’t absent in the combustion of wood.

PM 2Ring said:

wookiemeister said:

PM 2Ring said:

But potassium oxide is very reactive stuff. It’ll react with water to make potassium hydroxide. But it also has a strong affinity for carbon dioxide, reacting to form potassium carbonate.

so it will react with co2 in the absence of water?

Sure; but water isn’t absent in the combustion of wood.

the original equation ripped from Wikipedia by the looks of it

potassium carbonate itself seems to be only a water softner

Manufacture of soft soaps

The saponification of fats with KOH is used to prepare the corresponding “potassium soaps”, which are softer than the more common sodium hydroxide-derived soaps. Because of their softness and greater solubility, potassium soaps require less water to liquefy, and can thus contain more cleaning agent than liquefied sodium soaps.

its the KOH that does the washing component by reacting with grease not the KCO3 which just softens the water

wookiemeister said:

the original equation ripped from Wikipedia by the looks of it

No.

wookiemeister said:

The saponification of fats with KOH is used to prepare the corresponding “potassium soaps”,

….
its the KOH that does the washing component by reacting with grease not the KCO3 which just softens the water

Soap should not contain any unreacted hydroxide.

PM 2Ring said:

wookiemeister said:

The saponification of fats with KOH is used to prepare the corresponding “potassium soaps”,

….
its the KOH that does the washing component by reacting with grease not the KCO3 which just softens the water

Soap should not contain any unreacted hydroxide.

they react the KOH with oil/fat/grease to make soap

in theory you need a fool proof way of making sure theres no KOH left over or you start stripping your skin very slowly and turning you into soap. they’ve got this pH balanced soap now that means that the soap is slightly acidic

In Memoirs of a Napoleonic Foot Soldier some of the troops get together to share the little they have gathered from a scorched earth landscape. There was some peas and a bloke had managed to find some fat which was tipped in to enrich the peas. But they couldn’t eat them they burned the throat. Instead of adding fat the poor bastard had put in soap and ruined the little bit of food they had eaten in a few days.

I’ve often thought of getting some sodium hydroxide and reacting it with some olive oil to make soap but couldn’t be arsed

Skunkworks said:

In Memoirs of a Napoleonic Foot Soldier some of the troops get together to share the little they have gathered from a scorched earth landscape. There was some peas and a bloke had managed to find some fat which was tipped in to enrich the peas. But they couldn’t eat them they burned the throat. Instead of adding fat the poor bastard had put in soap and ruined the little bit of food they had eaten in a few days.

so they just ate him instead

you’d throttle someone like that in those kinds of circumstances

wookiemeister said:

PM 2Ring said:

Soap should not contain any unreacted hydroxide.

they react the KOH with oil/fat/grease to make soap

Indeed.

wookiemeister said:

in theory you need a fool proof way of making sure theres no KOH left over or you start stripping your skin very slowly and turning you into soap.

It’s not exactly rocket science.

PM 2Ring said:

wookiemeister said:

PM 2Ring said:

Soap should not contain any unreacted hydroxide.

they react the KOH with oil/fat/grease to make soap

Indeed.

wookiemeister said:

in theory you need a fool proof way of making sure theres no KOH left over or you start stripping your skin very slowly and turning you into soap.

It’s not exactly rocket science.

well my chemistry teacher said that its actually a bit of black magic when it comes to making soap, you normally have your own recipe that you follow to refine and make efficient the process and make the soap safe without making it greasy rather than soapy or caustic

wookiemeister said:

Skunkworks said:

In Memoirs of a Napoleonic Foot Soldier some of the troops get together to share the little they have gathered from a scorched earth landscape. There was some peas and a bloke had managed to find some fat which was tipped in to enrich the peas. But they couldn’t eat them they burned the throat. Instead of adding fat the poor bastard had put in soap and ruined the little bit of food they had eaten in a few days.

so they just ate him instead

you’d throttle someone like that in those kinds of circumstances

They didn’t, too weak to care a great deal, just a few tears. And I guess a bit frozen fat would look a lot like a bit of frozen peasants soap. They found something in a jar and had no clue what it was, they put it on a fire and it was honey. Je reckoned those calories probably saved his life.

Skunkworks said:

wookiemeister said:

Skunkworks said:

In Memoirs of a Napoleonic Foot Soldier some of the troops get together to share the little they have gathered from a scorched earth landscape. There was some peas and a bloke had managed to find some fat which was tipped in to enrich the peas. But they couldn’t eat them they burned the throat. Instead of adding fat the poor bastard had put in soap and ruined the little bit of food they had eaten in a few days.

so they just ate him instead

you’d throttle someone like that in those kinds of circumstances

They didn’t, too weak to care a great deal, just a few tears. And I guess a bit frozen fat would look a lot like a bit of frozen peasants soap. They found something in a jar and had no clue what it was, they put it on a fire and it was honey. Je reckoned those calories probably saved his life.

I’ve looked through these military books in the past and wondered how on earth people put up with stupidity

one reason they prefer younger people in the military is not for strength – its stupidity, younger people don’t know any better. an officer might tell a younger man to storm a machine gun post and they’d get killed in the process. an older person will tell them to fuck off and come up with a better plan or expect a (fragging)

i’m always amazed the german stayed in Stalingrad instead of telling the generals to go to hell and stay there if they wanted and be outnumbered, outgunned and isolated.

I guess basic human nature as a herd animal means that we are doomed to follow silly orders by the tribal leader.

thanks troops.

This is the greatest moment of your life and you’re off somewhere missing it.

• This is the greatest moment of your life and you’re off somewhere missing it.

Took you long enough…

PM 2Ring said:

wookiemeister said:

PM 2Ring said:

But potassium oxide is very reactive stuff. It’ll react with water to make potassium hydroxide. But it also has a strong affinity for carbon dioxide, reacting to form potassium carbonate.

so it will react with co2 in the absence of water?

Sure; but water isn’t absent in the combustion of wood.

Potassium carbonate is actually the direct product of decomposition that occurs in the ash. It is quite difficult to make the oxide from a potassium salt by thermal means. Potassium carbonate melts before it decomposes and this happens at high temperatures.

The potassium hydroxide comes from the hydrolysis of the potassium carbonate, which is the reverse of the reaction that OCDC posted above. However, the situation is more complex than this.

Much of the calcium is present as the carbonate too, but some is present at calcium oxide. This hydrates to calcium hydroxide. This in turn reacts with the soluble potassium carbonate, precipitating calcium carbonate. As a result, one is left with a solution of potassium hydroxide. In most ash, calcium is much more abundant than potassium. Some ashes are particularly high in potassium though, including bracken ash.

The reaction takes some time to complete. I usually leave it overnight. You can follow the reaction by measuring the pH or by testing the solution for a ‘soapy’ feel.

Nice concise explanation there, morrie.

Michael V said:

Nice concise explanation there, morrie.

tks, MV. :)

thanks Morrie. I can understand that easily :)

morrie said:

Potassium carbonate is actually the direct product of decomposition that occurs in the ash. It is quite difficult to make the oxide from a potassium salt by thermal means. Potassium carbonate melts before it decomposes and this happens at high temperatures.

The potassium hydroxide comes from the hydrolysis of the potassium carbonate, which is the reverse of the reaction that OCDC posted above. However, the situation is more complex than this.

Much of the calcium is present as the carbonate too, but some is present at calcium oxide. This hydrates to calcium hydroxide. This in turn reacts with the soluble potassium carbonate, precipitating calcium carbonate. As a result, one is left with a solution of potassium hydroxide. In most ash, calcium is much more abundant than potassium. Some ashes are particularly high in potassium though, including bracken ash.

The reaction takes some time to complete. I usually leave it overnight. You can follow the reaction by measuring the pH or by testing the solution for a ‘soapy’ feel.

Thanks, Morrie.

FWIW, I wasn’t implying that potassium oxide is formed in wood combustion, except maybe as a short-lived intermediate product, due to the oxidation of potassium salts. But I guess that with so much carbon (and oxygen) available, direct carbonate formation makes a lot of sense. OTOH, carbonates do tend to be unstable at high temperatures…

PM 2Ring said:

morrie said:

Potassium carbonate is actually the direct product of decomposition that occurs in the ash. It is quite difficult to make the oxide from a potassium salt by thermal means. Potassium carbonate melts before it decomposes and this happens at high temperatures.

The potassium hydroxide comes from the hydrolysis of the potassium carbonate, which is the reverse of the reaction that OCDC posted above. However, the situation is more complex than this.

Much of the calcium is present as the carbonate too, but some is present at calcium oxide. This hydrates to calcium hydroxide. This in turn reacts with the soluble potassium carbonate, precipitating calcium carbonate. As a result, one is left with a solution of potassium hydroxide. In most ash, calcium is much more abundant than potassium. Some ashes are particularly high in potassium though, including bracken ash.

The reaction takes some time to complete. I usually leave it overnight. You can follow the reaction by measuring the pH or by testing the solution for a ‘soapy’ feel.

Thanks, Morrie.

FWIW, I wasn’t implying that potassium oxide is formed in wood combustion, except maybe as a short-lived intermediate product, due to the oxidation of potassium salts. But I guess that with so much carbon (and oxygen) available, direct carbonate formation makes a lot of sense. OTOH, carbonates do tend to be unstable at high temperatures…

yeah they release CO2

so i’m assuming morrie knows what he’s talking about

wookiemeister said:

PM 2Ring said:

morrie said:

Potassium carbonate is actually the direct product of decomposition that occurs in the ash. It is quite difficult to make the oxide from a potassium salt by thermal means. Potassium carbonate melts before it decomposes and this happens at high temperatures.

The potassium hydroxide comes from the hydrolysis of the potassium carbonate, which is the reverse of the reaction that OCDC posted above. However, the situation is more complex than this.

Much of the calcium is present as the carbonate too, but some is present at calcium oxide. This hydrates to calcium hydroxide. This in turn reacts with the soluble potassium carbonate, precipitating calcium carbonate. As a result, one is left with a solution of potassium hydroxide. In most ash, calcium is much more abundant than potassium. Some ashes are particularly high in potassium though, including bracken ash.

The reaction takes some time to complete. I usually leave it overnight. You can follow the reaction by measuring the pH or by testing the solution for a ‘soapy’ feel.

Thanks, Morrie.

FWIW, I wasn’t implying that potassium oxide is formed in wood combustion, except maybe as a short-lived intermediate product, due to the oxidation of potassium salts. But I guess that with so much carbon (and oxygen) available, direct carbonate formation makes a lot of sense. OTOH, carbonates do tend to be unstable at high temperatures…

yeah they release CO2

so i’m assuming morrie knows what he’s talking about

If you search on the topic, as I have done in the past, you will learn something about the composition of wood ash, its variability, and its relationship to combustion conditions in the case of wood.

morrie said:

wookiemeister said:

PM 2Ring said:

Thanks, Morrie.

FWIW, I wasn’t implying that potassium oxide is formed in wood combustion, except maybe as a short-lived intermediate product, due to the oxidation of potassium salts. But I guess that with so much carbon (and oxygen) available, direct carbonate formation makes a lot of sense. OTOH, carbonates do tend to be unstable at high temperatures…

yeah they release CO2

so i’m assuming morrie knows what he’s talking about

If you search on the topic, as I have done in the past, you will learn something about the composition of wood ash, its variability, and its relationship to combustion conditions in the case of wood.

link?

I’ve seen the wood ash link to soap before but never investigated much beyond that

wookiemeister said:

morrie said:

wookiemeister said:

yeah they release CO2

so i’m assuming morrie knows what he’s talking about

If you search on the topic, as I have done in the past, you will learn something about the composition of wood ash, its variability, and its relationship to combustion conditions in the case of wood.

link?

I’ve seen the wood ash link to soap before but never investigated much beyond that

Its up to you to search it I’s afraid. I don’t have links to everything I research over the years. But calcium and potassium are not present as oxides in the ash. IIRC it gets even more complicated, with mixed salts.But the explanation that I gave describes the overall situation in aqueous solution of the ash.

As I said, it is difficult to produce potassium oxide by thermal means. I advised a research group of this fact once. They didn’t believe me at first…..

hey PM

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