Question

Arrange $\text{AgF},\text{ AgCl, AgBr}$and $\text{AgI}$ in the increasing order of solubility in water.
A.$AgBr<AgI<AgCl<AgF$
B.$AgI<AgBr<AgCl<AgF$
C.$AgI<AgCl<AgBr<AgF$
D.None of the above.

Answer 1

Hint: The order of solubility in water is based on the covalent character. If there is an increase in covalent character then they will be less soluble in water. Because we know that like dissolves like. As water is ionic in nature so if there is more covalent character then it will be less soluble in water.

Complete step by step answer:
To understand the solubility of silver halides, let us first talk about the covalent bond and ionic bond.
Covalent bond: The compound in which two atoms share their electrons to link together, is known as covalent bond. As they share electrons to each other so they do not have any polarity. If the atoms are too much different i.e. in their size then polarity can be there.
Ionic bond: The bond by which the two atoms can link together by donating or accepting the electrons, is known as ionic bond. They have polarities i.e. if an atom donates electrons then it will be positively charged and if they accept electrons then it will be negatively charged.
For the solubility, we know that like dissolves in like. For example: Ionic compounds (Compounds which have ionic bonds) will dissolve in ionic solvents (Solvents in which ionic bond is there). And the covalent compounds(Compounds in which covalent bond is present) will dissolve in covalent solvents(solvent in which molecules are linked by covalent bond).
In the given question, the solvent is water which is an ionic solvent i.e. gain and loss of electrons. But the compounds i.e. silver halides are covalent in nature. So the property of solubility will be less for the compounds in which more covalent character will be present.
In the silver halides the rate of covalent character is as: As we move down in a group the covalent character is increasing. Hence the order of solubility in water will be as: $AgI<AgBr<AgCl<AgF$.
Hence, B is the correct option.

Note:
As we move down in a group the order of covalent character increases because as we move down in a group electronegativity of the halides decreases. So the electronegativity difference between the silver and halides decreases on moving down in a group. Hence, covalent character increases down the group.