How to Prepare Sodium Metabisulfite Solution

Sodium metabisulfite (Na₂S₂O₅) solution is commonly used in laboratories and industry as an antioxidant and disinfectant. Follow these steps to prepare a standard aqueous sodium metabisulfite solution:

Materials Needed

• Sodium metabisulfite powder
• Distilled or deionized water
• Weighing balance
• Volumetric flask or beaker
• Stirring rod or magnetic stirrer
• Protective gloves and goggles (for safety)

Preparation Steps

• Determine desired concentration:
  Decide the final volume and desired concentration of your sodium metabisulfite solution (for example, 1% w/v or 10% w/v).
• Calculate required amount:
  Amount (g) = Desired concentration (%) × Final volume (mL) / 100
  For 100 mL of 10% solution: 10 × 100 / 100 = 10 grams.
• Weigh the sodium metabisulfite:
  Accurately weigh the calculated amount of sodium metabisulfite.
• Add water:
  Pour about 80% of the final volume of distilled water into your beaker or flask.
• Dissolve the solute:
  Add the sodium metabisulfite powder to the water. Stir gently with a stirring rod (or use a magnetic stirrer) until fully dissolved.
• Transfer and dilute:
  Transfer the solution into a volumetric flask, if available, and add distilled water to reach the exact final volume.

Storage and Safety Tips

• Store the solution in a tightly closed, labeled bottle away from light and heat.
• Use safety gloves and goggles, as sodium metabisulfite can be irritating to skin and eyes.
• Prepare fresh solution if possible, as sodium metabisulfite can degrade over time.

Note: Dispose of any waste according to local regulations, and always consult your specific protocol or supervisor for additional directions.