# Reaction between hydrobromic acid and sodium borate

Write the reaction for a a sodium borate solution being titrated by hydrobromic acid, assuming sodium borate is represented by $$\ce{Na3BO3(aq)}$$.

I think this is a simple double replacement reaction:

$$\ce{Na3BO3(aq) + 3 HBr(aq) -> 3 NaBr(aq) + H3BO3(aq)}\tag{R1}$$

Official solution without explanation:

$$\ce{Na3BO3(aq) + HBr(aq) -> 2 NaBr(aq) + NaH2BO3(aq) }\tag{R2}$$

I don't understand how the official reaction was reached. Why should a sodium cation take the place of a hydrogen?

• It is rather $\ce{Na[B(OH)4]}$ Nov 25 at 6:53
• The whole task seems to me like being made up. Who would use HBr for titration and end titration with alkalic solution ? I also do not believe much in Na3BO3(aq). Nov 25 at 7:39
• Don't forget, in contrast to e.g., $\ce{S}$ in $\ce{H2SO4}$, $\ce{B}$ in $\ce{H3BO3}$ (or $\ce{B(OH)3}$) still has the electron gap characteristic for Lewis acids like $\ce{AlCl3}$. Nov 25 at 7:40
• Poutnik is right. $\ce{Na3BO3}$ does not exist. Nov 25 at 21:46
• @Maurice Googling "trisodium orthoborate, na3bo3" give me 168 hits. The promising results are this and this. Nov 26 at 5:39