I am a high school student and was studying about the effects of heating orthoboric acid, and I saw two textbooks putting different statements.

One book says,

On heating above 370K, orthoboric acid forms metaboric acid, which on further heating forms boric oxide.
$\ce{H3BO3->[∆] HBO2->[∆] B2O3}$

Another book says the following reactions:

$\ce{H3BO3->[100°C]HBO2->[160°C]H2B4O7->[red heat]B2O3}$

I searched on Wikipedia, and it says the following:

Boric acid is soluble in boiling water. When heated above 170°C, it dehydrates, forming metaboric acid ($\ce{HBO2}$):
$\ce{H3BO3 → HBO2 + H2O}$
Metaboric acid is a white, cubic crystalline solid and is only slightly soluble in water. Metaboric acid melts at about 236°C, and when heated above about 300°C further dehydrates, forming tetraboric acid, also called pyroboric acid ($\ce{H2B4O7}$):
$\ce{4HBO2 → H2B4O7 + H2O}$
The term boric acid may sometimes refer to any of these compounds. Further heating (to about 330°C) leads to boron trioxide.
$\ce{H2B4O7 → 2 B2O3 + H2O}$

I am really confused. Which one of the three is correct? Is there any finer detail?

  • 1
    $\begingroup$ All are correct but 2 and 3 are complete whereas 1 is incomplete. $\endgroup$ Jun 19, 2021 at 9:40
  • 5
    $\begingroup$ All of them are correct. In 2nd reaction, the "red heat reaction" was meant to be the reaction occurring at 330 °C although "red heat" has its own meaning: chemistry.stackexchange.com/questions/108167/… $\endgroup$ Jun 19, 2021 at 9:47
  • 5
    $\begingroup$ Also in 1st reaction, "further heating" meant that temperature is increased from 160 °C to 330 °C. $\endgroup$ Jun 19, 2021 at 9:50


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