What is Na2S2O5? Important knowledge about Na2S2O5.

1. Definition of Na₂S₂O₅

Sodium metabisulfite (Na₂S₂O₅), also known as sodium pyrosulfite, is a chemical widely used in various industrial and food applications. This compound is also referred to as Sodium metabisulfite in English. In a molecule of Na₂S₂O₅, there are two sodium (Na) atoms, two sulfur (S) atoms, and five oxygen (O) atoms. Therefore, the molar mass of Na₂S₂O₅ is 190.107 g/mol. Its ionic structure consists of two sodium ions and one metabisulfite ion.

2. Properties of Na₂S₂O₅

2.1 Physical properties of Na₂S₂O₅: Sodium metabisulfite typically appears as a white powder or granules with a slightly distinctive smell. This compound has a pH range from 4 to 5 when dissolved in water.

2.2 Chemical properties of Na₂S₂O₅: Sodium metabisulfite easily reacts with acids to produce SO₂ gas. This compound can also react with various metals and non-metals to form different compounds.

3. Common chemical equations of Na₂S₂O₅

• Reaction with acid: Na₂S₂O₅ + 2HCl -> 2NaCl + SO₂ + H₂O
• Reaction with metal: Na₂S₂O₅ + 2K -> 2Na + K₂S₂O₅
• Reaction with non-metal: Na₂S₂O₅ + Br₂ -> Na₂S₂O₆ + 2NaBr
• Reaction with salt: Na₂S₂O₅ + CaCl₂ -> 2NaCl + CaS₂O₅

4. Synthesis of Na₂S₂O₅

4.1 Laboratory synthesis of Na₂S₂O₅: Typically, Na₂S₂O₅ is synthesized by reacting SO₂ with a solution of NaOH: SO₂ + 2NaOH -> Na₂S₂O₅ + H₂O.

4.2 Industrial synthesis of Na₂S₂O₅: In industry, Na₂S₂O₅ is usually produced through the reaction between SO₂, water, and NaOH under high pressure.