This chemical reaction involves the formation and interconversion of sulfur dioxide (SO2), sodium sulfite (Na2SO3), and sulfurous acid (H2SO3).

The reaction can be represented as:

SO2 + Na2SO3 + H2SO3 -> 2NaHSO3

In this reaction, sulfur dioxide reacts with sodium sulfite and sulfurous acid to produce sodium hydrogen sulfite.

Here's a brief explanation of the reaction steps:

Sulfur dioxide (SO2) reacts with water (H2O) to form sulfurous acid (H2SO3):
SO2 + H2O -> H2SO3

Sulfurous acid (H2SO3) then reacts with sodium hydroxide (NaOH) to produce sodium sulfite (Na2SO3):
H2SO3 + 2NaOH -> Na2SO3 + 2H2O

Finally, sodium sulfite (Na2SO3) reacts with sulfur dioxide (SO2) and sulfurous acid (H2SO3) to form sodium hydrogen sulfite (NaHSO3):
Na2SO3 + SO2 + H2SO3 -> 2NaHSO3

This reaction is a complex series of steps that involve the interconversion of sulfur dioxide, sodium sulfite, and sulfurous acid ions.