COMEDK2023Chemistryp Block Elements (Group 13 & 14)
The order of acidic strength of boron trihalides is
Options
- ABI ₃ < BBr ₃ < BCl ₃ < BF ₃
- BBF ₃ < BCl ₃ < BBr ₃ < BI ₃
- CBBr ₃ < BCl ₃ < BF ₃ < BI ₃
- DBCl ₃ < BBr ₃ < BI ₃ < BF ₃
Correct answer
B. BF ₃ < BCl ₃ < BBr ₃ < BI ₃
Step-by-step solution
Boron trihalides are Lewis acids. The back bonding determines its acidic strength, more is the -back bonding, less is the acidity. Thus, due to better overlapping of orbitals it promotes better -back bonding, hence BF ₃ is least acidic in nature. Thus, order of acidic strength is BF ₃ < BCl ₃ < BBr ₃ < BI ₃ .