If sulfurous acid is present, it will be oxidized to sulfuric acid and precipitated as barium sulfate by the barium chlorid.
If a precipitate forms on the addition of barium chlorid the presence of sulfurous acid is indicated.
If sulfurous acid is present a deep blue color forms at once.
|sulfurous acid |
A colorless solution of sulfur dioxide in water, characterized by a suffocating sulfurous odor. It is used as a bleaching agent, preservative, and disinfectant. Chemical formula: H2SO3.