Preparation of 2% Sodium Metabisulfite Solution

A 2% sodium metabisulfite solution is commonly used in laboratories as a preservative or antioxidant. Below are the steps to prepare a 2% (w/v) sodium metabisulfite solution.

Materials Required

  • Sodium metabisulfite (Na2S2O5) powder
  • Distilled water
  • Beaker
  • Stirring rod or magnetic stirrer
  • Measuring cylinder
  • Weighing balance
  • Volumetric flask or measuring flask (100 mL or 1 L as needed)
  • Label

Procedure

  1. Calculate the amount of sodium metabisulfite needed. For a 2% w/v (weight/volume) solution, dissolve 2 grams of sodium metabisulfite in enough distilled water to make a final volume of 100 mL.
    For 1 liter, use 20 grams in 1000 mL.
  2. Weigh 2 grams of sodium metabisulfite powder using the weighing balance.
  3. Pour about 80 mL of distilled water into a beaker.
  4. Add the weighed sodium metabisulfite to the beaker.
  5. Stir the solution using a stirring rod or magnetic stirrer until the powder completely dissolves.
  6. Transfer the contents to a 100 mL volumetric flask or measuring cylinder.
  7. Rinse the beaker with a small amount of distilled water and add the rinsing to the volumetric flask.
  8. Add more distilled water to the flask until the total volume reaches exactly 100 mL.
  9. Mix thoroughly to ensure homogeneity.
  10. Label the container appropriately with the solution name, concentration, and date of preparation.

Storage

  • Store the solution in a tightly closed bottle.
  • Keep in a cool, dry place, away from direct sunlight.
  • Use fresh solution, as sodium metabisulfite solutions can degrade over time.

Note: Handle all chemicals with care. Wear appropriate personal protective equipment (gloves, goggles, lab coat).