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Romix
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Neutralization of Vinegar with KOH
Dissolved half a can out of mayonnaise with insoluble in water plant ash in 2 500ml bottles of 10% vinegar.
PH still neutral, will filter it soon when it'll stop fizzing.
Ok the question is how much KOH I need to add to neutralize all the Acetates in solution??
Knowing that 1ml of Glacial Acetic acid weighs 1.5 grams.
How to work it out?
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j_sum1
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Add KOH solution slowly.
Use pH paper
Stop when neutral.
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Romix
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PH is neutral right now.
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j_sum1
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Ash solution contains K2CO3.
Vinegar contains acetic acid.
Not sure what the mayonnaise is for.
You have a weak acid and weak base and the salts from the neutralisation reaction. Seems like you have created yourself a buffer solution. It will
take quite a bit of strong acid or strong base to shift it.
If you want a neutral solution, I am not at all sure what your problem is.
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Romix
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Quote: Originally posted by j_sum1  | Ash solution contains K2CO3.
Vinegar contains acetic acid.
Not sure what the mayonnaise is for.
You have a weak acid and weak base and the salts from the neutralisation reaction. Seems like you have created yourself a buffer solution. It will
take quite a bit of strong acid or strong base to shift it.
If you want a neutral solution, I am not at all sure what your problem is. |
I meant that insoluble in water plant ash were stored in a can out of mayonnaise...
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Romix
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And I've used half a can of ash.
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j_sum1
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Well, assuming your ash is pure potassium carbonate (which is a really dumb assumption but anyway)
You will have a mixture containing potassium ions, carbonate/bicarbonate ions (depending on the pH), acetate ions and dissolved CO2.
You can get rid of most of the CO2 by boiling it for a while.
Actual pH will depend on the exact proportions (which you don't know). You have a couple of different acid-base equilibrium reactions going on so it
will be a dog of a thing to calculate anyway. Potassium acetate is a basic salt. But then you have other impurities.
If you want to put it on your garden, leave it for a long time to expel the CO2 and reach equilibrium. Then test pH and see if it is in the range you
want for your garden.
If you want to do more than that then there are a number of good YT videos of qualitative tests that you can do on wood ash to determine ions present.
But nothing much quantitative is within the reach of the amateur chemist.
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DraconicAcid
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It's neutral, and you want to make it more neutral? Come back when you know what you're talking about.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Romix
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Chucked KOH in solution of Acetates until basic PH like 6 teaspoons.
A lot of white hydroxides precipitated. That is pain in the ass to filter.
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Romix
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My PH papers not turning red on diluted acetic acid!
Will make it basic with K2CO3, KOH doesn't work every thing dissolves in it's excess!!
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Romix
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Hydroxides that dissolved in excess KOH, dropped with K2CO3.
[Edited on 20-8-2023 by Romix]
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Romix
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What cation it could be??
Obtained from insoluble in water plant ash dissolved in vinegar and precipitated with K2CO3.
It dissolves in excess KOH.
Hydroxides and Carbonates of which are both white.
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Romix
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Hydroxides that didn't dissolve in excess KOH were white too, but turning grey standing on air drying.
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Rainwater
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https://www.sigmaaldrich.com/US/en/technical-documents/techn...
Scroll down until you see the table.
From your starting material these cations are likly to disolive in vinegar and percipitate carbonates on the addition of K2CO3
Mg
Ca
Br
Fe
Iron can be ruled out because of the color of your percipitate
Barium will be in trace amounts
Edit:
A flame test will help determine the cation.
Magnesium will be white
Calcium an orange red
[Edited on 20-8-2023 by Rainwater]
"You can't do that" - challenge accepted
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B(a)P
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Slight typo, should be Ba. Surely there would not be meaningful quantities of barium in wood ash?
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Romix
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Thinking about getting Spectrometer, to ID cations in plant ash, one day I've seen 2 of them selling on ebay under 20£ on auction. There's few there
now, but buy now and very very expensive, will wait for a better deal!
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Romix
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Checking if Mg(OH)2 precipitated with KOH out of pure MgSO4·7H2O will dissolve in excess of KOH.
Also will give a go crystalizing K2SO4.
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Romix
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| Quote: Originally posted by Rainwater | https://www.sigmaaldrich.com/US/en/technical-documents/techn...
Scroll down until you see the table.
From your starting material these cations are likly to disolive in vinegar and percipitate carbonates on the addition of K2CO3
Mg
Ca
Br
Fe
Iron can be ruled out because of the color of your percipitate
Barium will be in trace amounts
Edit:
A flame test will help determine the cation.
Magnesium will be white
Calcium an orange red
[Edited on 20-8-2023 by Rainwater] |
Thank you for advice. Flame testing them is a good idea, didn't knew about the difference. Will do that tomorrow, it's too dark now. Do I need to
dissolve a sample for a flame test or can use hydroxides and carbonates as they are.
[Edited on 20-8-2023 by Romix]
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Rainwater
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| Quote: Originally posted by B(a)P |
Slight typo, should be Ba. Surely there would not be meaningful quantities of barium in wood ash? |
Correct, peer review proved itself again.
barium hydroxide as a very effective pesticide against kudzu and it is a common mineral where I live, the largest barium mine is my state is about 30
minutes from here.
It shows up in well water and soil test. Some countys require private wells to be tested biannualy, and a consentration over 1.5ppm will close your
well.
Edit:
disoliveing some in HCl solution, then apply to a stick and dry, and repeat to build up a thick layer of salt. Add a few drops of methanol/ethanol.
And apply a flame.
[Edited on 20-8-2023 by Rainwater]
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B(a)P
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| Quote: Originally posted by Rainwater | | Quote: Originally posted by B(a)P |
Slight typo, should be Ba. Surely there would not be meaningful quantities of barium in wood ash? |
Correct, peer review proved itself again.
barium hydroxide as a very effective pesticide against kudzu and it is a common mineral where I live, the largest barium mine is my state is about 30
minutes from here.
It shows up in well water and soil test. Some countys require private wells to be tested biannualy, and a consentration over 1.5ppm will close your
well. |
Interesting stuff! The mineralisation of local areas can be really fascinating. Very off topic, some time ago I was part of a team that designed and
constructed a new training facility in a remote part of North Queensland. A water supply was required, but the granite in the area contained fine
grained disseminated pitchblende and the concentrations of uranium in the water made it non-potable, so we ended up installing an RO plant and a
little solar farm to support it.
Nice idea on the flame test, given it is a mix though will it give a meaningful result? I guess at least it will be a reasonable presence absence test
for elements that tend to be dominant in flame tests.
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Romix
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Flame testing is very difficult, just tried testing K2SO4 in solution, it didn't change flame color, same for burning sample of Mg(OH)2.
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Rainwater
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Im stupid. Completely forgot about this.
You can selectively percipitate calcium using sulfuric acid (or equivalent)
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Romix
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| Quote: Originally posted by Rainwater | Im stupid. Completely forgot about this.
You can selectively percipitate calcium using sulfuric acid (or equivalent) |
Barium too...
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B(a)P
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Yes, but unless you live up the road from Rainwater you will not have any barium.
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Romix
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No, not Calcium!
Cation that dissolved in excess KOH, and dropped with K2CO3 after acidification with vinegar.
Added K2SO4 to a sample dissolved in vinegar. No precipitate forming!
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