Question

Alumina is insoluble in water because

• A. it is a covalent compound
• B. it has high lattice energy and low heat of hydration
• C. it has low lattice energy and high heat of hydration
• D. $\ce{Al^{3+}}$ and $\ce{O^{2-}}$ ions are not excessively hydrated.

Answer 1

Answer: (B)

it has high lattice energy and low heat of hydration

Answer 2

${Al_2O_3}$ has high lattice energy and low heat of hydration. It is therefore, insoluble in water.