CHRIS25
National Hazard
Posts: 951
Registered: 6-4-2012
Location: Ireland
Member Is Offline
Mood: No Mood
|
|
Tests for Boron in Borax
How would I, if it is possible, be able to determine the amount of boron that is in Borax, or any sodium borate or tetraborate compound? Something
here that I can not discover for myself.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
|
|
|
sasan
Hazard to Self
Posts: 92
Registered: 22-2-2014
Location: TEHRAN / IRAN
Member Is Offline
Mood: Radiative
|
|
Chris it is a hard question.boron compounds like borax and boric acid have easy procedure for producing in industry.the commercial ones are nearly 99%
pure.so if you want know the purity of your reagent it is the answere
There are methods for determining the boron in its compunds but I dont think if you can find some data about that
[Edited on 6-7-2014 by sasan]
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
@ Sasan:
It's not the purity of Borax he's looking at.
@ Chris:
Accurately weigh a sufficient amount of Borax and dissolve it in sufficient water to give a solution of about 0.3 M.
Acidify the solution according to:
Na2B4O7·10H2O(aq) + 2 HCl(aq) ===> 4 H3BO3(s) + 2 NaCl(aq) + 5 H2O(l)
The boric acid (H3BO3) is poorly soluble in cold water, so after this step, chill in a refrigerator or on an ice bath: the boric acid will crystallise
out as slightly greasy looking flakes.
Filter these off and wash carefully with small aliquots of iced water to remove the NaCl and any excess HCl.
Dry the boric acid and weigh it. From that weight the w% boron in the Borax can be calculated. This is approximate because boric acid does have
limited solubility in cold water, so you will slightly underestimate the boron content.
[Edited on 6-7-2014 by blogfast25]
|
|
|
CHRIS25
National Hazard
Posts: 951
Registered: 6-4-2012
Location: Ireland
Member Is Offline
Mood: No Mood
|
|
Ah, thanks Gert (and Sasan). Not a whimsical question, I need to determine the amount of Boron in samples so much appreciated, I was afraid that it
might have been more complex than this, so glad to read it is fairly straightforward.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
You have reasons to not trust the empirical formula of the product you have bought?
|
|
|
CHRIS25
National Hazard
Posts: 951
Registered: 6-4-2012
Location: Ireland
Member Is Offline
Mood: No Mood
|
|
Getting a product from an Irish farmers shop in a clear bag with no labelling and it simply says "Boron Powder' yes it is difficult to know the
source, except that upon questioning he told me the company/manufacturer's name was solubor (USA as I understand) and further hunting revealed a Boron
content of 21%, but Solubor is an octaborate tetrahydrate and the 50 kg sack the shop owner showed me had 17.5% sodium borate, not tetraborate
otherwise this would be classed as Borax, which the EU seems to be banning slowly with stupid ridiculously invented health warnings. Yes it is all
rather hazy this info. I know what wolfram says about Borax being 11.3% Boron, but I do not seem to be able to find it at the moment, very strange
indeed.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
The octahydrate and decahydrate often referred to may be one and the same. Borax's formula is written in two ways: Na2B4O7•10H2O or
Na2[B4O5(OH)4]•8H2O but they are one and the same product (CAS 1303-96-4) with a molar mass of 381.38 g/mol. The latter notation is closer to
reality as we understand it today. With the molar mass of boron being 10.81 g/mol:
W% boron = (4 x 10.81) / 381.38 x 100 % = 11.34 w% boron
[Edited on 6-7-2014 by blogfast25]
|
|
|
CHRIS25
National Hazard
Posts: 951
Registered: 6-4-2012
Location: Ireland
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by blogfast25  | The octahydrate and decahydrate often referred to may be one and the same. Borax's formula is written in two ways: Na2B4O7•10H2O or
Na2[B4O5(OH)4]•8H2O but they are one and the same product (CAS 1303-96-4) with a molar mass of 381.38 g/mol. The latter notation is closer to
reality as we understand it today. With the molar mass of boron being 10.81 g/mol:
W% boron = (4 x 10.81) / 381.38 x 100 % = 11.34 w% boron
[Edited on 6-7-2014 by blogfast25] |
Hi, no solubor is OctaBorate with formula: Na2B8013
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
That's an anhydrate. About 25 w% boron.
The tetrahydrate of that octaborate has MM = 412.48 g/mol and boron w% of 21 w%.
Yep, I think you best get analysing!
[Edited on 6-7-2014 by blogfast25]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
