When a Lewis base reacts with Lewis acid, a covalent bond is produced.
Best example, CO2 Lewis acid reacts with OH- Lewis base to give HCO3- bicarbonate ion, BF3 boron trifluoride behaves as a Lewis acid & NH3 ammonia as a Lewis base.
Calcium oxide (CaO) behaves as a Lewis base, & sulphur trioxide (SO3) as a Lewis acid in the reaction between the 2.
CaO + SO3 ------------------> CaSO4
Lewis Lewis Calcium
Base acid sulphate
The Lewis concept of acids & bases suffers from the following limitations.
- It fails to account for the relative strength of bases & acids, as it is not based on ionization.
- An acid-base reaction essence an electron-transfer reaction should be pretty fast. Hence, many Lewis acid-base reactions are slow.
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