The first chemical equation is the reaction of sulfur dioxide (SO2) with water (H2O) to produce sulfurous acid (H2SO3):

SO2 + H2O -> H2SO3

The second chemical equation is the reaction of silicon dioxide (SiO2) with water (H2O) to produce silicic acid (H2SiO3):

SiO2 + H2O -> H2SiO3