S

Secondary Standard

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Also Known AsStandardized solution, working standard solution, titration secondary standard

What is Secondary Standard?

A secondary standard is a standard solution whose concentration has been determined by comparison (standardization) against a primary standard solution, rather than being prepared directly from a pure substance. Secondary standards are used because many reagents useful as titrants cannot be obtained in primary standard grade. Common secondary standards include NaOH (standardized against KHP) and Na₂S₂O₃ (standardized against potassium dichromate).

Properties & Characteristics

Concentration determined by titration against primary standard. Less stable than primary standards — requires periodic re-standardization. Common secondary standards: NaOH (absorbs CO₂, must be standardized), KMnO₄ (not primary grade), Na₂S₂O₃ (iodometric titrations), HCl solution (volatile). Must be stored correctly to maintain concentration.

Uses & Applications

Volumetric analysis and titrations. Analytical chemistry quality control. Clinical and industrial laboratories. Food and pharmaceutical analysis. Environmental testing. Teaching laboratory analytical chemistry.

Safety Information

Secondary standard solutions may be corrosive (NaOH, HCl), oxidizing (KMnO₄, K₂Cr₂O₇), or toxic (K₂Cr₂O₇ — carcinogenic). Handle with appropriate precautions. Store correctly to prevent decomposition or contamination.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Secondary Standard
Synonyms Standardized solution, working standard solution, titration secondary standard

Frequently Asked Questions

A secondary standard is a standard solution whose concentration has been determined by comparison (standardization) against a primary standard solution, rather than being prepared directly from a pure substance. Secondary standards are used because many reagents useful as titrants cannot be obtained in primary standard grade. Common secondary standards include NaOH (standardized against KHP) and Na₂S₂O₃ (standardized against potassium dichromate).

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