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What it is. This EDTA titrant contains 0.05 moles of disodium EDTA dihydrate per liter, is labeled 0.1 N, and comes in a 1-gallon size. It is a clear, colorless complexometric titrant for calcium, magnesium, and other metals in water and process samples.
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Why 0.05 M is labeled 0.1 N. EDTA binds divalent metal ions such as calcium and magnesium one-to-one, and each mole corresponds to two equivalents of charge. Expressed as normality, 0.05 M EDTA is therefore 0.1 N. Molarity is the more direct basis for calculations.
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What each milliliter delivers. One milliliter contains 0.05 millimole of EDTA, which complexes 2.004 mg of calcium, 1.215 mg of magnesium, or the equivalent of 5.005 mg of calcium carbonate (calculated). These factors convert titration volume directly into sample concentration.
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A versatile working strength. At 0.05 M, the titrant suits moderately hard water, process water, and metal assays where 0.01 M would need large volumes and 0.1 M would give too few milliliters for good precision.
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Calculating hardness. Multiply the milliliters of titrant used by 5.005 to get milligrams of calcium carbonate equivalent, then divide by the sample volume in liters to report mg/L as CaCO3 (calculated). Subtract a reagent blank first and use the standardized molarity when it differs from 0.05 M.
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Running a hardness titration. Buffer the sample near pH 10 with an ammonia buffer, add Eriochrome Black T, and titrate from wine red to clear blue. Lab Pro offers Eriochrome Black T Indicator, Ammonium Chloride, ACS Grade, and Ammonium Hydroxide 28 to 30% Solution, ACS Grade for that buffer system.
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How EDTA works. EDTA is a hexadentate chelating agent that wraps around a metal ion through two nitrogen atoms and four carboxylate groups, forming a stable one-to-one complex. That predictable stoichiometry is what makes EDTA titrations accurate.
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Standardization and care. For critical work, standardize against calcium carbonate or zinc, keep the container tightly closed, and use deionized water and metal-free labware. The 1-gallon size provides one consistent lot for routine testing over an extended period.
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Related EDTA products. For higher metal levels, see EDTA Titrant 0.2 N / 0.1 M, 1 gallon or EDTA Disodium Solution, 0.1 M (0.2 N). To prepare custom strengths, use EDTA Disodium Salt Dihydrate, ACS Grade.
Technical Specifications
| Chemical Name |
Ethylenediaminetetraacetic acid disodium salt dihydrate, aqueous solution |
| Synonyms |
EDTA titrant, disodium EDTA solution |
| CAS Numbers |
6381-92-6 (disodium EDTA dihydrate); 7732-18-5 (water) |
| EC Number (active) |
205-358-3 |
| Formula (active) |
C10H14N2Na2O8·2H2O |
| Molecular Weight (active) |
372.24 g/mol |
| Concentration |
0.05 M (0.1 N) |
| EDTA Content |
About 18.6 g/L dihydrate (calculated) |
| EDTA per mL |
0.050 mmol |
| Titration Equivalence |
1.00 mL = 2.004 mg Ca, 1.215 mg Mg, or 5.005 mg CaCO3 (calculated) |
| Binding Ratio |
1:1 EDTA to metal ion |
| Appearance |
Clear, colorless liquid |
| Physical State |
Liquid, aqueous solution |
| Storage |
Room temperature, tightly closed |
| Package Size |
1 gallon |
Applications / Common Uses
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Water hardness: Determines total hardness with Eriochrome Black T.
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Calcium and magnesium: Titrates Ca and Mg in water and process samples.
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Metal assays: Quantifies zinc, nickel, and other divalent metals.
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Boiler and cooling water: Monitors hardness in industrial water systems.
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Teaching labs: Demonstrates complexometric titration.
Storage, Handling & Shipping
Store the solution tightly closed at room temperature to prevent evaporation, which would raise its concentration. Keep it away from strong oxidizers and metal-containing materials, and use clean, metal-free labware so trace metals do not consume EDTA before titration.
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Incompatible materials: Strong oxidizers, strong acids, and metal salts.
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Personal protection: Safety glasses and nitrile gloves.
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Spill response: Absorb with inert material and rinse the area with water.
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First aid: Eyes: rinse with water for several minutes. Ingestion: rinse mouth and seek medical advice.
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