Question
Explain why the following compounds behave as Lewis acids?
- $BCl_3$.
- $AlCl_3$.
✓
Answer
Lewis acids are basically electron deficient species. They can readily accept electron from Lewis bases, which are electron rich and can donate electrons.
In $BCl_3$, the central atom boron is electron deficient and has only six electrons. Hence it is termed as Lewis acid. It can readily accept electron from ammonia or its derivatives.
Reaction:
In $AlCl_3$, Al has empty p orbitals to accept the electrons to complete its octet, so it acts as a lewis acid.
Structure of $AlCl _3$ :
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