If you want to make 75 mL of a 0.015 M solution of B(OH)3 in water, how many grams of B(OH)3 would you need?
mass=molemass*concentration*volume
mass=MolmassB(OH)3*.015*.075
Boron hydroxide is an unusual hydroxide, it is acidic, not basic. Often it is written as H3BO3, boric acid.