Primary standard
A primary standard in chemistry is a reliable, readily quantified substance. Features of a primary standard include:
1. High purity
2. Stability (low reactivity)
3. Low hygroscopicity and efflorescence
4. High solubility (if used in titration)
5. High equivalent weight
Some examples of primary standards according to the European Pharmacopoeia:
- Arsenic trioxide for standardisation of iodine and cerium(IV) sulfate solutions
- Benzoic acid for standardisation of TBAH in methanol solutions
- Potassium bromate (KBrO3) for standardisation of sodium thiosulfate solutions
- Potassium hydrogen phthalate (usually called KHP) for standardisation of sodium and potassium hydroxide and perchloric acid in acetic acid solutions
- Sodium carbonate for standardisation of hydrochloric, sulfuric acid and nitric acid solutions
- Sodium chloride for standardisation of silver nitrate solutions
- Sulfanilic acid for standardisation of sodium nitrite solutions
- Zinc powder for standardisation of EDTA solutions
External link
Source
- Skoog and West. Fundamentals of Analytical Chemistry. (3rd ed.) Holt, Rinehart, and Winston, 1976.