AllChemicals — The Online Chemical Glossary | https://allchemicals.info/chemical/660-primary-standard
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Quick Reference
Also Known As
Primary titrimetric standard, standard substance, certified reference material (CRM)
What is Primary Standard?
A highly pure, stable substance of known composition used to prepare standard solutions for calibrating titrations. Properties: high purity, stability in air, non-hygroscopic, high molar mass, and reacts according to a simple stoichiometry. Examples include potassium hydrogen phthalate and sodium carbonate.
Properties & Characteristics
A primary standard is a highly pure, stable substance of known composition that can be weighed accurately and dissolved to prepare a solution of exactly known concentration without further standardisation. Requirements: (1) high purity (>99.9%); (2) stable to drying conditions; (3) non-hygroscopic; (4) high molar mass (reduces weighing error); (5) rapid and complete reaction in the intended titration. Examples: potassium hydrogen phthalate (KHP) for NaOH standardisation; Na₂CO₃ for HCl; K₂Cr₂O₇ for sodium thiosulfate.
Uses & Applications
Primary standards are used to standardise (determine exact concentration of) secondary standard solutions (NaOH, HCl, KMnO₄, Na₂S₂O₃). They are also used directly in titrations requiring a primary standard of the titrant. NIST and IUPAC-certified reference materials serve as primary standards in high-accuracy analytical work.
Safety Information
K₂Cr₂O₇ (primary standard for oxidimetry) is a Cr(VI) compound — carcinogenic, mutagenic, and a skin sensitiser. KHP and Na₂CO₃ are of low toxicity. Concentrated solutions of primary standard acids or bases prepared for titrimetry are corrosive. Always follow standard laboratory safety for all titrimetric reagents.
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
SynonymsPrimary titrimetric standard, standard substance, certified reference material (CRM)
Frequently Asked Questions
A highly pure, stable substance of known composition used to prepare standard solutions for calibrating titrations. Properties: high purity, stability in air, non-hygroscopic, high molar mass, and reacts according to a simple stoichiometry. Examples include potassium hydrogen phthalate and sodium carbonate.
Primary standards are used to standardise (determine exact concentration of) secondary standard solutions (NaOH, HCl, KMnO₄, Na₂S₂O₃). They are also used directly in titrations requiring a primary standard of the titrant. NIST and IUPAC-certified reference materials serve as primary standards in hig…
K₂Cr₂O₇ (primary standard for oxidimetry) is a Cr(VI) compound — carcinogenic, mutagenic, and a skin sensitiser. KHP and Na₂CO₃ are of low toxicity. Concentrated solutions of primary standard acids or bases prepared for titrimetry are corrosive. Always follow standard laboratory safety for all titri…
Editorial standards: Chemical data is sourced from peer-reviewed literature,
CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA,
and IAEA. For educational purposes only — always consult official SDS documentation and qualified
professionals before handling chemicals.
