Question

Account for the following observations:
(i) SF4 is easily hydrolysed whereas SF₆ is not easily hydrolysed
(ii) Chlorine water is a powerful bleaching agent.
(iii) Bi(V) is a stronger oxidising agent than Sb(V)

Answer 1

(I) Sulphur atom in sulphur tetrafluoride SF₄ is not protected as it is surrounded by only four atoms so, attack of water molecules can take place easily . In contrast , sulphur atom in sulphur hexafluoride, SF₆ is protected by six Fluorine atoms . Thus, attack by water molecules cannot take place easily.

(ii) chlorine water is a powerful bleaching agent. Actually, chlorine water produces nascent oxygen And we know, Nascent oxygen is responsible for bleaching agent. Reaction follows as Cl₂ + H₂O ——-> 2HCl + [O] ⇒nascent oxygen

(iii) due to inert pair effect , bismuth, Bi(V) can accept a pair of electrons to forms more stable Bi(III).

[ note :- +3 oxidation state of bismuth is more stable than +5 oxidation state]

Answer 2

(I) Sulphur atom in sulphur tetrafluoride SF₄ is not fully  protected as it is surrounded by only four atoms so, water molecules have lesser tendency to attack canthe sulfur atom. In contrast , sulphur atom in sulphur hexafluoride is completely packed by six fluorine atoms.Thus SF₆ is protected by six Fluorine atoms.Hence attack by water molecules cannot take place easily.

(ii) chlorine water is a powerful bleaching agent because chlorine water produces nascent oxygen in presence of sunlight.Nascent oxygen is responsible for bleaching agent. Reaction follows as,

Cl₂ + H₂O ——-> 2HCl + [O] ⇒nascent oxygen

(iii)  Bi(V) is a stronger oxidising agent than Sb(V) due to inert pair effect.It is due to inert pair effect,Sb cannot accept two electrons to form Sb(III) where as bismuth, Bi(V) can accept a pair of electrons to forms more stable Bi(III).