[magiccc]

What happens if I heat La2(C2O4)3? La2(C2O4)3 + 1,5O2--> La2O3 + 6CO2 ?

[Arkcon]

For one thing, in the chemical equation:

La₂(C₂O₄)₃ + 1,5O₂--> La₂O₃ + 6CO₂

You're using a fractional amount of oxygen reacting (which is acceptable sometimes, but whole numbers are often preferred.)

Lanthanides are called "rare earths" so its likely the oxalate roasts to a refractory oxide on heating.  But there's not really a way to be sure, in every case, just because we balance a chemcial equation.