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.
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You Will Need
- Chemistry techniques
- Balance
- 4 grams purified dihydrate ethylenediaminetetraacetic acid
- Desiccator
- 1L volumetric flask
- Powder funnel
- 1L purified water
- Stopper (optional)
Steps
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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.
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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.
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Step 2
Measure
Weigh 3.8 grams and transfer it into a volumetric flask using a powder funnel.
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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.
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Step 4
Mix
Swirl the solution until all of the powder has dissolved.
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Be patient -- it may take up to 15 minutes for the solution to be completely dissolved.
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Step 5
Add water and mix
Add more purified water until it reaches the 1-liter mark, and mix well.
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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.
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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.
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EDTA was first used as a medical treatment for heavy metal poisoning in the 1940s, and is still FDA-approved for that purpose.
