Aluminium trifluoride is insoluble in anhydrous HF but dissolves on addition of NaF. Aluminium trifluoride precipitates out of the resulting solution when gaseous $B F_{3}$ is bubbled through. Give reasons.

Open in App

Solution

Anhydrous HF is a covalent compound and forms strong intramolecular H bonds. It does not give fluoride ions and cannot dissolve $A l F_{3}$ in it. KF is an ionic compound and contains fluoride ions. It combines with $A l F_{3}$ to form the soluble complex.
$A l F_{3} + 3 N a F \to N a_{3} [A l F_{6}]$
B has small size and high electronegativity. It has mauch higher tendency for complex formation than Al. Hence, when $B F_{3}$ is added to above solution, $A l F_{3}$ is precipitated.
$N a_{3} [A l F_{6}] + 3 B F_{3} \to 3 N a B F_{4} + A l F_{3}$

Suggest Corrections

Similar questions

A l F_{3}

N a F

A l F_{3}

B F_{3}

A I F_{3}

H F

K F

{B F}_{3}

A I F_{3}

A l (O H)_{3}

Join BYJU'S Learning Program