Na3AlO3 is an aluminate of sodium- it is known as a solid and contains a polymeric anion.
Aluminium dissolves in sodium hydroxide solution to produce hydrogen.
The reaction is often written as if the product is Na3AlO3
Al+3NaOH = Na3AlO3 + H2
Some wise people put the Na3AlO3 in quotes to show that the exact form of the aluminum salt is not as shown.
This equation is wrong--the implication of it is that the OH- is deprotonated by Aluminium to produce hydrogen and O2-- this is not what happens.
Hydrogen is certainly evolved and there is aluminum in solution- however a better way of expressing this phenomenon is as follows
Aluminium is only unreactive to water because there is a layer of Al2O3 on the surface- strong nitric acid can be transported in Al containers quite safely because of this.
The NaOH removes the Al2O3, the water can then react with the aluminum
2Al+6H2O = 2Al(OH)3 + 3H2
The OH- keeps the Al(OH)3 in solution as Al(OH)4-
the overall reaction is
2Al + 6H2O + 2NaOH = 3H2 + 2NaAl(OH)4(aq)
Sodium aluminate.
2 Mg + 2 NaOH-------2 MgO + H2 + 2 Na 2 Al + 6 NaOH------2 Na3AlO3 + 3 H2