A reaction between ammonia and boron triflurdie is given below :
`:NH_(3)+BF_(3)toH_(3)N:BF_(3)`
Identify the acid and base in this reaction. Which theory explanis it ? What is the hybridsation of B and N in the additon compound ?

Explanation

Acid `:BF_(3)`,Base `=NH_(3)`
Their character is explanied on the basis of Lewis concept. Thus, `BF_(3)` is a Lewis acid while `NH_(3)` is a Lewis base In `BF_(3)` moleule, B atom is `sp^(2)` hybridised while in `NH_(3)` molecule, N atom is in `sp^(3)` hybridised state. In the formation of addition compound, B atom has taken up an electron pair from the N atom. Therefore, it undergoes a change in hybridisation from `sp^(2)` to `sp^(3)`. However. there is no change in hybridisation state of N in the addition compound `F_(3)B larrNH_3`.