1. If the ratio of NaOH to CO2 is 5: 9, it can be judged that CO2 is excessive, which can be directly expressed by this equation. NaOH+CO2=NaHCO32, if the ratio of CO2 to NaOH is 5: 9.

Then the reaction can be seen as two steps.

Step 1: NaOH+CO2=NaHCO3.

Reaction residual NaOH? (9-5=4 copies)

Then the reaction occurs: NaHCO3+NaOH=Na2CO3+H2O.

4 parts of NaHCO3 reacted, leaving (5-4= 1 part) NaHCO3.

The final products are NaHCO3 and Na2CO3, and the ratio is 1: 4.

Can also be written as a general equation:

9NaOH+5CO2=4Na2CO3+NaHCO3+4H2O