Hi Daniel,

Al2O3 reacts with NaOH as follows:

Al2O3 +6 NaOH ---->2 Al(OH)3 + 3Na2O.

Gentlemen, Al2O3 reacts with NaOH to form sodium aluminate, Na2Al2O4, which causes the dissolution of aluminum oxide.

Dear Sir. Concerning your issue about the solubility of Al2O3 in NaOH. I agree with Dr. Khaleel's answer. Crystalline Al2O3 at room temperature is hardly soluble in any solvent, even concentrated acid or alkali, for kinetic reasons. Only amorphous Al(OH)3 may be soluble. Al2O3 only reacts with as strong solvent as melted NaOH as previuosely described Dr. V. S. Sudavtsova.

Thanks

Dear sir Al2O3 isn’t soluble in NaOH but less soluble in acidic phase.

Simple non-ignited Al2O3 or Al(OH)3 is soluble in common acids or aqueous NaOH forming Al+3 salt (in case of acid) or NaAlO2 (with aq. NaOH). But ignited alumina is insoluble in common acids. However ignited Al2O3 thoug insoluble in conc. acids like HCl or HNO3 is soluble in NaOH on heating. In fact ignited alumina on fusion with NaOH forms NaAlO2 and H2O (2NaOH + Al2O3 = 2NaAlO2 + H2O). The mixture when treated with water forms a clear solution of Sodium aluminate.

This is possible because the electronegativity difference between aluminum and oxygen is small, unlike the difference between sodium and oxygen, for example (electronegativity increases across a period)

Aluminum oxide reacts with hot, concentrated sodium hydroxide solution to produce a colorless solution of sodium tetrahydroxoaluminate:

Al2O3+2NaOH+3H2O→2NaAl(OH)4

Yes Mr. Daniel , you can do it simply by using hot sodium hydroxide.