Q.White fumes appear around the bottle of anhydrous aluminium chloride. Give reason.

Step 1 - Nature of anhydrous AlCl3

Anhydrous AlCl3 is largely covalent (it exists as the dimer $\text{Al}_2\text{Cl}_6$ in the vapour and solid state) because the small, highly charged $\text{Al}^{3+}$ ion strongly polarises the chloride ions (Fajans' rules). Being covalent and having an electron-deficient aluminium centre, it is strongly hygroscopic.

Step 2 - Hydrolysis by atmospheric moisture

Step 3 - Why white fumes appear …

Recall AlCl3 is substantially covalent (Al2Cl6 dimer, Fajans' rules) and hygroscopic; write the hydrolysis equation with atmospheric water vapour; the HC …

• Thinking AlCl3 is purely ionic (like NaCl) since it is a metal chloride - its high charge density makes it substantially covalent.
• Forgetting to balance the hydrolysis equation (3 H2O, 3 HCl). …