Question

what is the effect of heating on orthoboric acid?give chemical equation​

Answer 1

Boric add, on heating, loses water in three different stages at different temperatures ultimately giving boron trioxide.

Answer 2

Answer:

Orthoboric acid when heated above 370K forms metabolic acid, HBO2 which on further heating yields boric oxide, B2O3

Explanation:

Orthoboric acid when heated above 370K forms metabolic acid, HBO2 which on further heating yields boric oxide, B2O3.

$2 \mathrm{H}_{3} \mathrm{BO}_{3} \frac{\Delta}{\rightleftharpoons-2 \mathrm{H}_{2} \mathrm{O}} 2 \mathrm{HBO}_{2} \frac{\Delta}{\rightleftharpoons-\mathrm{H}_{2} \mathrm{O}} \mathrm{B}_{2} \mathrm{O}_{3}$

On heating orthoboric acid$\left(\mathrm{H}_{3} \mathrm{BO}_{3}\right)$at $370 \mathrm{~K}$ or above, it changes to metabolic acid $\left(\mathrm{HBO}_{2}\right)$. On further heating, this yields boric oxide $\mathrm{B}_{2} \mathrm{O}_{3}$.

When boric acid$\left(\mathrm{H}_{3} \mathrm{BO}_{3}\right)$ is heated at $370 \mathrm{~K}$ it forms metabolic acid and water.

$\mathrm{H}_{3} \mathrm{BO}_{3} \underset{373 \mathrm{~K}}{\longrightarrow} \mathrm{HBO}_{2}+\mathrm{H}_{2} \mathrm{O}$

The product formed (metabolic acid) exists converted into Tetra boric acid  $410 \mathrm{~K}$ by losing water.

$4 \mathrm{HBO}_{2} \text { (Meta boric acid) } 47 \mathrm{CKH}_{2} \mathrm{~B}_{4} \mathrm{O}_{7}(\text { T etra boric acid })+\mathrm{H}_{2} \mathrm{O}$

Tetra boric acid at red heat temperature constitutes boron trioxide or borax by losing water.

$\mathrm{H}_{2} \mathrm{~B}_{4} \mathrm{O}_{7} \text { Red Heat } 2 \mathrm{~B}_{2} \mathrm{O}_{3}+\mathrm{H}_{2} \mathrm{O}$

The overall reaction exists as follows:

$\mathrm{H}_{3} \mathrm{BO}_{3} \underset{370 \mathrm{~K}}{\stackrel{\Delta}{\longrightarrow}} \underset{\text { Metaboric acid }}{\mathrm{HBO}_{2}} \stackrel{\Delta}{\longrightarrow} \underset{\text { Tetraboric acid }}{\mathrm{H}_{2} \mathrm{~B}_{3} \mathrm{O}_{7}} \stackrel{\Delta}{\longrightarrow} \mathrm{B}_{2} \mathrm{O}_{3}$.

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