Question

(a) Account for the following:
(i) $N{H}_3$ acts as a Lewis base.
(ii) $P{Cl}_3$ fumes in moist air.
(iii) Fluorine shows only $-1$ oxidation state.
(b) (i) Suggest any two fluorides of Xenon.
(ii) Write a method to prepare any one of the above mentioned Xenon fluorides.

Answer 1

(a)

(i) $N{H}_3$ acts a lewis base due to the presence of lone pair on nitrogen which are ready for donation.

(ii) $PC{l}_3$ fumes in moisture due the formation of $HCl$.

$PC{l}_3+H_{2}O⟶HCl+H_{3}P{O}_3$

(iii) Fluorine has outer electronic configuration $n{s}^{2}n{p}^5$, which requires only one $e^{-}$ to complete its p-shell. So by accepting an $e^{-}$ for completing its shell it shows $-1$ oxidation state. Moreover $F$ is highly electronegative.

(b)

(i) $2$ fluorides of Xenon:- $Xe{F}_2,Xe{F}_4$

(ii) Preparation:

$Xe+F_2⟶Xe{F}_2$

It is prepared by heating a mixture of $Xe$ and $F_2$ in the molecular ratio $1:5$ at ${400}^{o}C$ and $6$ atm in a sealed $Ni$ tube.

$Xe\left(g\right)+2F_2\left(g\right)\underset{7bar}{\overset{873K}{\to }}Xe{F}_4$