The complete ionic equation for the reaction between aluminum sulfate and sodium carbonate is:
2Al3+(aq) + 3SO42-(aq) + 2Na+(aq) + CO32-(aq) → Al2(CO3)3(s) + 3SO42-(aq) + 2Na+(aq)
The net ionic equation is obtained by eliminating the spectator ions (ions that appear on both sides of the equation and do not participate in the reaction). The spectator ions in this reaction are Na+ and SO42-. Therefore, the net ionic equation is:
2Al3+(aq) + 3CO32-(aq) → Al2(CO3)3(s)