In one of my books it is written that boron does not react with alkali but in another book it is written that it reacts with alkali.
Can any one help in clearing this confusion?
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3$\begingroup$ Could you show us those reactions? $\endgroup$– schneiderfelipeCommented Jan 31, 2017 at 11:19
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2$\begingroup$ When boron reacts with alkali the reaction is this. 3B+NaOH -> 2Na3BO3+3H2O $\endgroup$– Sarla Riya MishraCommented Jan 31, 2017 at 12:10
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3$\begingroup$ That equation shouldn't make sense to you. Boron is being oxidised from 0 to +3 but nothing is being reduced. $\endgroup$– orthocresolCommented Jan 31, 2017 at 13:14
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2 Answers
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Boron react with $\ce{NaOH}$ but under certain conditions. Boron exist in two form (1) crystalline form (2) amorphous form. Both forms are generally inert to chemical reactions and is unaffected by acids and alkali at normal conditions but at elevated temperature, concentrated oxidizing acids like nitric or sulfuric acids react with boron to yield boric acid. On the other hand, amorphous boron does react with fused alkali at high temperature to obtain trisodium borate:
$$\ce{2B(s) + 6NaOH(s) ->[t > 773K] 2Na3BO3(s) + 3H2(g) ^}$$
High purity, hydrated sodium metaborate(sodium tetrahydroxoborate, $\ce{Na[B(OH)4]}$) can also be produced from boron in a $\ce{NaOH-H2O}$ system. The process applied was called pressure alkaline leaching.
When fused in the presence of air at $\pu{350-400 ^\circ C}$, sodium metaborate is formed. You can find the reaction in this answer by @andselisk.
References
- https://onlinelibrary.wiley.com/doi/abs/10.1002/0471743984.vse1217
- Yin, B.W & Qin, S.Y & Zhang, Y.F & Zhang, Y (2014). Preparation of hydrated sodium metaborate from boron concentrate via pressure alkaline leaching. Guocheng Gongcheng Xuebao/The Chinese Journal of Process Engineering. 14. 258-265, (link)
answered Jan 31, 2017 at 14:21
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$\begingroup$ Could you provide other references for the reactions (not chemiday)? $\endgroup$ Commented Nov 17, 2020 at 10:48
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1$\begingroup$ @AshishAhuja see andselisk's answer: chemistry.stackexchange.com/questions/118485/… $\endgroup$ Commented Nov 17, 2020 at 10:54
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$\begingroup$ The first link appears not to involve Chemiday, but attempting to click on it gave me an antivirus firewall. I am unable to sustain an upvote until references more reliablexand secure are found. $\endgroup$ Commented Nov 23, 2020 at 19:38
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$\begingroup$ @OscarLanzi answer reconstructed, removed the dead link, removed all of chemiday BS. $\endgroup$ Commented Nov 24, 2020 at 5:04
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Your reaction is far from balanced but what you want seems to be trisodium borate.
According to this source (emphasis mine),
Boron reacts with fused sodium hydroxide to form sodium borate and hydrogen.
The cited reaction (already balanced) is the following:
$$\ce{2 B + 6 NaOH -> 2 Na3BO3 + 3 H2 ^}$$
This other source says something similar (again, emphasis mine),
It can also dissolve in alkalies and evolve hydrogen.
So, as it seems, boron reacts not with sodium hydroxide solutions, but with the pure, molten compound. This may be the source of confusion.
answered Jan 31, 2017 at 13:09