In volumetric titrations, standardization is the process of titrating a solution prepared from which of the following?

• A. A secondary standard solution of previously known molarity
• B. A solution whose concentration is determined solely from its labeled bottle concentration
• C. Any reagent of approximate concentration prepared by weighing an impure solid
• D. A primary standard substance of accurately known purity and mass

Answer: (D)

Verified step by step guidance

1. Understand that standardization in volumetric titrations involves determining the exact concentration of a titrant solution by reacting it with a substance of known purity and quantity.
2. Recognize that a primary standard is a substance that is highly pure, stable, non-hygroscopic, and has a known formula weight, making it suitable for accurate mass measurement.
3. Know that the primary standard substance is weighed accurately and dissolved to prepare a solution with a precisely known concentration.
4. Use the primary standard solution to titrate the titrant solution, allowing calculation of the titrant's exact molarity based on the stoichiometry of the reaction.
5. Conclude that standardization requires a primary standard substance of accurately known purity and mass, not a secondary standard or approximate reagent.