Question

What happens when 

(a)Borax is heated strongly, 

(b)Boric acid is added to water, 

(c) Aluminium is treated with dilute NaOH, 

(d)BF₃ is reacted with ammonia? 

Answer 1

(a) When heated, borax undergoes various transitions. It first loses water molecules and swells. Then, it turns into a transparent liquid, solidifying to form a glass-like material called borax bead. 

(b) When boric acid is added to water, it accepts electrons from –OH ion. Boric acid is sparingly soluble in cold water however fairly soluble in hot water. boric acid behaves as a weak monobasic acid. It doesn't act as a proton-donor, i.e., protonic acid, however, behaves as a Lewis-acid, i.e., it accepts a pair of electrons.

(c) Al reacts with dilute NaOH to form sodium tetrahydroxoaluminate(III). Hydrogen gas is liberated in the process. 

(d) BF3 (a Lewis acid) reacts with NH₃ (a Lewis base) to form an adduct. This results in a complete octet around B in BF₃. 

Comments

When borax is heated strongly it loses water molecules and  swells. Then it is converted into a transparent liquid, solidifying which will form a glass-like material also called borax bead.