The molecular equation for the chemical change is:
NaHCO3+H2SO4→Na2SO4+H2O+CO2
NaHCO3,H2SO4 and Na2SO4 are ionic compounds; so these are written in ionic forms.
Na++HCO−3+2H++SO2−4→2Na++SO2−4+H2O+CO2
Na+ and SO2−4 ions are spectator ions; hence these shall not appear in the final equation.
HCO−3+2H+→H2O+CO2
To make equal charges on both sides, HCO−3 should have a coefficient 2.
2HCO−3+2H+→H2O+CO2
In order to balance the hydrogen and carbon on both sides, the molecules of H2O and CO2 should have a coefficient 2 respectively.
2HCO−3+2H+=2H2O+2CO2
or HCO−3+H+=H2O+CO2
This is the balanced ionic equation.