`AIF_(2)` is soluble in `HF` only in presence of `KF`. It is due to the formation of

Options

A. `K_(3)[AlF_(3)H_(3)]`
B. `K_(3)[AlF_(6)]`
C. `AIH_(3)`
D. `K[AlF_(3)H]`

Answer

2

Explanation

Aluminium trifluorde is insoluble in anhydroous `HF` but dissoves on additon of `KF` beacause anhydrous `HF` is a covalent compound and is strongly `H-`bonded. Therefore, it does not yield `F^(-)` ion and hence `AlF_(3)` does not dissolve in `HF`. On the other hand, `KF` being an ionic compound contains `F^(-)` ions and hence combines with `AlF_(3)` to form the complex, thereby shifitng the equilibrium:
`underset("Insoluble")(AlF_(3))(s) overset(HF)(hArr) AlF_(3)(HF) overset(KF)(rarr) underset(("soluble complex"))underset("Pot. hexafluridoalumunate (III)")`