Which trihalide is not hydrolysed by water?

Question

Which trihalide is not hydrolysed by water? (A) NF3 (B) NCl3 (C) PCl3 (D) AsCl3

Tardigrade Admin · Accepted Answer

In the first stage of hydrolysis, an extra bond is formed by water molecule. While chlorine and the group 15 elements (except nitrogen) can expand their octet by using vacant d-orbitals of the valence shell, F and N cannot. As a result,

N F_{3}

is extremely stable.

Trihalides of P, As, Sb and Bi hydrolyse readily.

N F_{3} + H_{2} O (l) \to

No hydrolysis

NC l_{3} + 3 H_{2} O (l) \to N H_{3} + 3 H OCl

PC l_{3} + 3 H_{2} O (l) \to H_{3} P O_{3} + 3 H Cl

2 A s C l_{3} + 3 H_{2} O \to 6 H Cl + A s_{2} O_{3}

Notes: A.

S b C l_{3}

and

B i C l_{3}

also hydrolyze to form basic oxochlorides.

B i C l_{2} + H_{2} O ⇌ B i OCl + 2 H Cl

B. Hydrolysis of

NC l_{3}

is thought to proceed by stepwise replacement of chlorine, the lone pair on N-atom bonding to hydrogen atom of a water molecule

Solution

N H C l_{2} + H_{2} O \to N H_{2} Cl + H ClO

N H_{2} Cl + H_{2} O \to N H_{3} + H ClO

Q. Which trihalide is not hydrolysed by water?

$N F_{3}$

$NC l_{3}$

$PC l_{3}$

$A s C l_{3}$

Q. Which trihalide is not hydrolysed by water?

NF3​

NCl3​

PCl3​

AsCl3​

$N F_{3}$

$NC l_{3}$

$PC l_{3}$

$A s C l_{3}$