0.1 N Potassium Dichromate VS
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
Dissolve about 5 g of potassium dichromate in 1000 mL of water.
Standardization
▲See Volumetric Solutions, 1. Introduction.
See Titrimetry ⟨541⟩.
Standardize by one of the following procedures. [Note—Other standardization procedures may be used. See Volumetric Solutions, 2. Preparation and Standardization, 2.3 Standardization.]
Standardization with visual endpoint: ▲ (USP 1-May-2021) Transfer 25.0 mL of this solution to a glass-stoppered, 500-mL flask, add 2 g of potassium iodide, ▲
▲ (USP 1-May-2021) dilute with 200 mL of water, add 5 mL of hydrochloric acid, allow to stand for 10 min in a dark place, and titrate the liberated iodine with 0.1 N sodium thiosulfate VS, adding 3 mL of starch TS as the endpoint is approached. Carry out a blank determination.
▲N = [mL (sample) − mL (blank)] × Na₂S₂O₃ N Na₂S₂O₃/ 25.0
Standardization with potentiometric endpoint: Transfer 10.0 mL of this solution to a glass-stoppered, 500-mL flask, add 2 g of potassium iodide, dilute with 200 mL of water, add 5 mL of hydrochloric acid, allow to stand for 10 min in a dark place, and titrate the liberated iodine with 0.1 N sodium thiosulfate VS potentiometrically using a combined platinum (Pt) electrode. Carry out a blank determination.
▲N = [mL (sample) − mL (blank)] × Na₂S₂O₃ N Na₂S₂O₃/ 10.0
▲ (USP 1-May-2021)
[Note—If this volumetric solution is used in a qualitative application such as pH adjustment, dissolution medium, or diluent, its standardization is not required.]
