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How to Prepare a Standard EDTA Solution

When converted to a standard solution, EDTA is a useful chemical compound for titration applications such as determining the metallic content of various solutions.

Instructions

  • Step 1: Dry and cool Measure 4 grams of purified dihydrate ethylenediaminetetraacetic acid on the balance and dry at 80 degrees Celsius for one hour before letting it cool to room temperature in the desiccator.
  • TIP: The salt will contain about 0.3 percent moisture after drying and cooling. Make a note to correct the salt's weight in your calculation of the molarity of the finished solution.
  • Step 2: Measure Weigh 3.8 grams and transfer it into a volumetric flask using a powder funnel.
  • Step 3: Add water Rinse the funnel by pouring a small amount of distilled or deionized water through it before removing the salt. Then add enough extra purified water to make 700 milliliters. Use a dry, uncontaminated container with a non-glass stopper.
  • Step 4: Mix Swirl the solution until all of the powder has dissolved.
  • TIP: Be patient -- it may take up to 15 minutes for the solution to be completely dissolved.
  • Step 5: Add water and mix Add more purified water until it reaches the 1-liter mark, and mix well.
  • Step 6: Calculate molarity Calculate the molarity, or molar concentration, of the solution. The result should be at or very close to 0.01 M.
  • Step 7: Finish Store the solution with a stopper. If you plan to use it for titration, it's good practice to conduct the experiment while the solution is still fresh.
  • FACT: EDTA was first used as a medical treatment for heavy metal poisoning in the 1940s, and is still FDA-approved for that purpose.

You Will Need

  • Chemistry techniques
  • Balance
  • 4 grams purified dihydrate ethylenediaminetetraacetic acid
  • Desiccator
  • 1L volumetric flask
  • Powder funnel
  • 1L purified water
  • Stopper (optional)

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