Which of the following halides react(s) with AgNO3 (aq) to give a precipitate that dissolves in Na2 S2O3(aq)?

Question

Which of the following halides react(s) with AgNO3 (aq) to give a precipitate that dissolves in Na2 S2O3(aq)? (A) HCI (B) HF (C) HBr (D) HI

Tardigrade Admin · Accepted Answer

Solubilities of silver halides in water decreases from fluoride

(A g F)

to iodide

(A g I)

. Silver fluoride is readialy soluble in water, hence when

A g N O_{3}

solution is added to

H F

solution (

H F

being weak acid, its solution maintain very low concentration of

F^{-}

) no precipitate of

A g F

is formed.

H Cl, H B r

and

H I

being all strong acid, forms precipitates of

A g Cl, A g B r

and

A g I

when

A g N O_{3}

solution is added to their aqueous solution

H Cl (a q) + A g N O_{3} (a q) \to Curdy white A g Cl (s) + H N O_{3} (a q)

H B r (a q) + A g N O_{3} (a q) \to Pale yellow A g B r (s) + H N O_{3} (a q)

H I (a q) + A g N O_{3} (a q) \to yellow A g I (s) + H N O_{3} (a q)

The solubilities decreases from

A g Cl

to

A g l, A g Cl

dissolves in aqueous ammonia,

A g B r

dissolves only slightly in concentrated ammonia while

A g I

does not dissolve in ammonia solution.

N a_{2} S_{2} O_{3}

solution dissolve all three,

A g Cl, A g B r, A g l

by forming complex

[A g (S_{2} O_{3})_{2}]^{3 -}

as

S_{2} O_{3}^{2 -}

is a stronger complexing agent than ammonia.

Q. Which of the following halides react(s) with AgNO3​ (aq) to give a precipitate that dissolves in Na2​S2​O3​(aq)?