Alumina is insoluble in water because: — p Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Alumina (Al2O3) is a highly stable ionic compound. Step 2: Due to the high charges (+3 on Al and -2 on O) and small ionic radii of both the aluminum and oxide ions, the electrostatic forces of attraction in the crystal lattice are extremely strong. Step 3: This results in an exceptionally high lattice energy that cannot be overcome by the hydration energy of the ions (low heat of hydration), making alumina insoluble in water (option b).