Which of the following statements is correct?

Question

Which of the following statements is correct? (A) BCl3 and AlCl3 are both Lewis acids and BCl3 is stronger than AlCl3 (B) Both BCl3 and AlCl3 are Lewis acids and AlCl3 is stronger than BCl3 (C) Both BCl3 and AlCl3 are equally strong Lewis acids (D) Both BCl3 and AlCl3 are not Lewis acids

Tardigrade Admin · Accepted Answer

In BCl3,pπ -pπ back-donation occurs between the vacant 2p-orbital of 'B' and fully-filled 3p-orbital of Cl of a B-Cl bond. This pπ -pπ overlapping is not much effective, because of dissimilar sizes of 2p and 3p-orbitals. But in AlCl3 , pπ -pπ overlapping is more effective, because p-orbitals of Al and Cl belongs to the same energy levels and hence, they are of similar sizes. As a result of back-donation, the electron-deficiency of Al atom gets more compensated as compared with 'B' in BCl3 and therefore, Lewis acid character of AlCl3 is lesser than that of BCl3 .

Q. Which of the following statements is correct?

$BC l_{3}$ and $A lC l_{3}$ are both Lewis acids and $BC l_{3}$ is stronger than $A lC l_{3}$

Both $BC l_{3}$ and $A lC l_{3}$ are Lewis acids and $A lC l_{3}$ is stronger than $BC l_{3}$

Both $BC l_{3}$ and $A lC l_{3}$ are equally strong Lewis acids

Both $BC l_{3}$ and $A lC l_{3}$ are not Lewis acids

Q. Which of the following statements is correct?

BCl3​ and AlCl3​ are both Lewis acids and BCl3​ is stronger than AlCl3​

Both BCl3​ and AlCl3​ are Lewis acids and AlCl3​ is stronger than BCl3​

Both BCl3​ and AlCl3​ are equally strong Lewis acids

Both BCl3​ and AlCl3​ are not Lewis acids

$BC l_{3}$ and $A lC l_{3}$ are both Lewis acids and $BC l_{3}$ is stronger than $A lC l_{3}$

Both $BC l_{3}$ and $A lC l_{3}$ are Lewis acids and $A lC l_{3}$ is stronger than $BC l_{3}$

Both $BC l_{3}$ and $A lC l_{3}$ are equally strong Lewis acids

Both $BC l_{3}$ and $A lC l_{3}$ are not Lewis acids