Question

$Al{F}_3$ is soluble in HF only in presence of KF. its is due to the formation of:

• A. $Al{H}_3$
• B. $K\left[Al{F}_{3}H\right]$
• C. $K_3\left[Al{F}_3{H}_3\right]$
• D. $K_3\left[Al{F}_6\right]$

Answer 1

The correct option is D $K_3\left[Al{F}_6\right]$

$Al{F}_3$ is insoluble in the anhydrous $HF$ because the $F^{-}$ ions are not available in intermolecular hydrogen bonded $HF$, but it becomes soluble in the presence of $KF$ due to the formation of soluble complex, $K_3\left[Al{F}_6\right]$

$Al{F}_3+3KF\to K_3\left[Al{F}_6\right]$