When sodium metabisulfite and calcium hydroxide are mixed, a series of chemical reactions occur between them. Firstly, sodium metabisulfite will decompose into sodium sulfite and sulfur dioxide:

Na2S2O5 → Na2SO3 + SO2

Then, sulfur dioxide reacts with calcium hydroxide to produce calcium thiosulfate:

SO2 + Ca(OH)2 → CaSO3 + H2O

Finally, the reaction between calcium thiosulfate and calcium hydroxide generates calcium sulfate and water:

Na2S2O5 + Ca(OH)2 → CaSO4 + Na2SO3 + H2O

This reaction process produces calcium sulfate, sodium sulfite, and water. Calcium sulfate is a white powdery solid commonly used in fields such as building materials, paper making, and fertilizers. Sodium sulfite is a white crystalline solid commonly used in food additives, bleaches, disinfectants, and other fields.

reaction between sodium metabisulfite and calcium hydroxide

During this reaction process, sulfur dioxide gas is also generated. Sulfur dioxide is a colorless and irritating gas commonly used in fields such as disinfection, sterilization, and bleaching. However, sulfur dioxide is also a harmful gas, and long-term exposure can pose a threat to human health.

Overall, the reaction between sodium metabisulfite and calcium hydroxide is an interesting chemical reaction. It can not only produce useful substances, but also release energy. However, when conducting this reaction, we also need to pay attention to safety and avoid the harm of sulfur dioxide to human health.