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Topic: KOH + H3BO3 -> ?  (Read 19211 times)

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Offline Catsceo

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KOH + H3BO3 -> ?
« on: August 09, 2010, 11:47:25 PM »
Well hello everyone, I was wondering if reacting potassium hydroxide with boric acid would yield K3BO3 or KBO2?  Wolfram Alpha seems to say KBO2 (K+ O-B=O-).  Any ideas guys?
I <3 Bi, I, and Br! :D

Offline vmelkon

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Re: KOH + H3BO3 -> ?
« Reply #1 on: August 11, 2010, 11:24:11 AM »
I don't know much about H3BO3. It seems to be a special case. Perhaps not all H+ are released when dissolved in water.
In H3BO3, the boron is connected to 3 OH groups which means it has a +3 charge.
In KBO2, the B also has a +3 charge so the question is, what would be the reaction?

KOH + H3BO3 = KBO2 + H20 + H20?

KBO2 is the metaborate.
K3BO3 is potassium orthoborate.
There is also K2B2O7 is the borate.

It is a strange anion.

Offline Catsceo

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Re: KOH + H3BO3 -> ?
« Reply #2 on: August 11, 2010, 01:25:15 PM »
I don't know much about H3BO3. It seems to be a special case. Perhaps not all H+ are released when dissolved in water.
In H3BO3, the boron is connected to 3 OH groups which means it has a +3 charge.
In KBO2, the B also has a +3 charge so the question is, what would be the reaction?

KOH + H3BO3 = KBO2 + H20 + H20?

KBO2 is the metaborate.
K3BO3 is potassium orthoborate.
There is also K2B2O7 is the borate.

It is a strange anion.


Yeah, I guess I should be asking what its molecular formula will be.  The salt I produced is white and 'fluffy', and breaks up into small grains easily.
I <3 Bi, I, and Br! :D

Offline vmelkon

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Re: KOH + H3BO3 -> ?
« Reply #3 on: August 12, 2010, 12:57:10 PM »
I believe I understand. The chemistry is similar to Aluminum for example in the case of
KOH + Al(OH)3 = KAlO2 + 2H20

I'm sure everyone has seen NaOH added to Al. In which case NaOH attacks the Al2O3 and also the Al itself.
NaOH + Al(OH)3 = NaAlO2 + 2H20
2NaOH + 2Al + 2H2O = 2NaAlO2 + 3H2

so theoretically, boric acid is boron hydroxide and the reaction is
KOH + B(OH)3 = KBO2 + 2H20

(but I'm an amateur and there is no guarantee that the above is correct)

Offline Cesium-137

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Re: KOH + H3BO3 -> ?
« Reply #4 on: October 17, 2010, 09:50:56 PM »
H3BO3 is not a traditional acid, in that it does not deprotonate to produce H+. In aqueous solutions, H3BO3 attracts a water molecule, bonds to its oxygen and produces H3O+ via deprotonation of the newly bonded water molecule. The acid in this case is actually HB(OH)4. In anhydrous conditions it acts as an electron acceptor, not necessarily an H+ donor. Due to its character as a lewis acid, I would expect B(OH)3 to pick up the OH- from KOH, forming K+ B(OH)4- as a salt. The presence of water as a solvent or otherwise may affect the products of the reaction.

Offline Catsceo

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Re: KOH + H3BO3 -> ?
« Reply #5 on: November 13, 2010, 04:26:01 PM »
H3BO3 is not a traditional acid, in that it does not deprotonate to produce H+. In aqueous solutions, H3BO3 attracts a water molecule, bonds to its oxygen and produces H3O+ via deprotonation of the newly bonded water molecule. The acid in this case is actually HB(OH)4. In anhydrous conditions it acts as an electron acceptor, not necessarily an H+ donor. Due to its character as a lewis acid, I would expect B(OH)3 to pick up the OH- from KOH, forming K+ B(OH)4- as a salt. The presence of water as a solvent or otherwise may affect the products of the reaction.

This is correct.  I did some heating on the compound that was formed and it seemed to decompose, releasing water.  :)
I <3 Bi, I, and Br! :D

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