Question

I need to write a balance equation of the decomposition of aluminum carbonate.

I know the starting "reactant" is Al2(CO3)3 but would the "product' be 2Al + 3(CO3) ? Thanks

Answer 1

No. Most carbonates decompose on heating to CO2 + the oxide.
Al2(CO3)3 ==> Al2O3 + CO2
I will leave it for you to balance.

Note:
CaCO3 ==> CaO + O2
MgCO3 ==> MgO + CO2
Na2CO3 ==> Na2O + CO2
etc.