${\mathrm{H}}_3{\mathrm{BO}}_3\stackrel{{\mathrm{T}}_1}{⟶}\mathrm{X}\stackrel{{\mathrm{T}}_2}{⟶}\mathrm{Y}\stackrel{\text{ red hot }}{⟶}{\mathrm{B}}_2{\mathrm{O}}_3$ if temperature ${\mathrm{T}}_1<{\mathrm{T}}_2$ then x and y respectively are:

impact of the temperature at 100 °C, ${\mathrm{H}}_3{\mathrm{BO}}_3$ Metaboric acid is produced by the loss of water. ${\mathrm{H}}_3{\mathrm{BO}}_3\stackrel{{100}^{\circ }\mathrm{C}}{⟶}{\mathrm{HBO}}_2+{\mathrm{H}}_2\mathrm{O}$ At 160 °C, tetraboric acid is formed from metaboric acid.$4{\mathrm{HBO}}_2\stackrel{{160}^{\circ }\mathrm{C}}{⟶}{\mathrm{H}}_2{\mathrm{B}}_4{\mathrm{O}}_7+{\mathrm{H}}_2\mathrm{O}$ Strong heating results in the production of ${\mathrm{B}}_2{\mathrm{O}}_3$.

${\mathrm{H}}_2{\mathrm{B}}_4{\mathrm{O}}_7\to 2{\mathrm{B}}_2{\mathrm{O}}_3+{\mathrm{H}}_2\mathrm{O}$.