What is the end product formed when SO2 is captured in scrubbers using lime or limestone?

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Multiple Choice

What is the end product formed when SO2 is captured in scrubbers using lime or limestone?

When SO2 is removed from flue gases with a lime or limestone scrubber, the reaction that occurs ends up forming gypsum, calcium sulfate dihydrate (CaSO4·2H2O). The SO2 dissolves in the alkaline slurry and, through intermediate steps, combines with calcium to become calcium sulfate as a solid precipitate. This gypsum byproduct is stable and often sold for uses like drywall, turning pollution control into a useful product. The other options would only arise if different reagents or oxidation states were involved (for example, a sodium-based scrubber could produce sodium sulfate, or a different chemical pathway could leave calcium carbonate as a reactant rather than the final solid).

When SO2 is removed from flue gases with a lime or limestone scrubber, the reaction that occurs ends up forming gypsum, calcium sulfate dihydrate (CaSO4·2H2O). The SO2 dissolves in the alkaline slurry and, through intermediate steps, combines with calcium to become calcium sulfate as a solid precipitate. This gypsum byproduct is stable and often sold for uses like drywall, turning pollution control into a useful product. The other options would only arise if different reagents or oxidation states were involved (for example, a sodium-based scrubber could produce sodium sulfate, or a different chemical pathway could leave calcium carbonate as a reactant rather than the final solid).

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