What is the balanced equation of sulfur dioxide plus water?

Answer 1

There are different possible answers here; in fact several of them. The two most obvious ones are:

S + O2 --> SO2 : SO2 + H2O --> H2SO3

and:

2 S + 3 O2 --> 2 SO3 : 2 SO3 + 2 H2O --> 2 H2SO4

That just shows the balance; it does not point out whether the reaction requires several steps or special catalysts etc. For example, the second reaction might need a catalyst like platinum or vanadium pentoxide, or it could take a different course like:

2S +2O2 --> 2SO2 : 2SO2 + 2H2O --> 2H2SO3 : 2 H2SO3 + O2 --> 2 H2SO4

Answer 2

Equation

SO2 + H2O ----> H2SO3 (Sulfurous acid is produced)

Answer 3

The reaction is :
2 SO2 + 2 H2O + O2 = 2 H2SO4