Textbook question

[Annabella_Amato_1I]

In this case, is B(OH)3 acting as a Lewis base or Lewis acid? And why? Thanks!

[Kyle Walsh 2J]

Hi! So in this question, B(OH)3 is acting as the Lewis acid, as it is accepting the electron pair from the (OH)- to turn into B(OH)4-. You can double check this by confirming that H30+ is formed, meaning that the original compound was acidic and the conjugate is basic. Hope this helped!

[Anh Trinh 1J]

B(OH)3 is acting as a Lewis acid because in the product side, it accepts the OH- from the water molecule. Also, comparing the water molecule on the reaction and product side, you can see that it had 4 H atoms and 2 atoms before the reaction, and only 3 H atoms and 1 O atoms are left, so it has donated the OH- to B(OH)3.

[Jiapeng Han 1C]

Like AlCl3, B in B(OH)3 also has empty orbital which means that it could accept electron pair from the OH- group, meaning it is a Lewis acid.