Ceric Sulfate as a Volumetric Oxidizing Agent. I. Preparation and Standardization of Solutions. Determination of Calcium

A new volumetric oxidizing agent

“…If an oxidizing agent is to be of extensive value in analytical work, it must meet a number of requirements, among the more important of which are the following: (1) it must compare favorably in its properties with oxidizing agents already in use; ^2) it must be available in some convenient form so that solutions of it can be prepared readily; (3) it must be either a primary standard or a substance which can be standardized easily, and preferably against a primary reduction standard; (4) it must serve as its own indicator when the equivalence-point is reached, or suitable indicators for use with it must be available; (5) it must react stoichiometrically with a considerable number of reducing agents. These points will be discussed in the order mentioned.…”

Indicators for Determining Chromium and Vanadium in Alloy Steels

“…To determine the indicator blanks with variations in concentration of oxidizing agent, volume of solution, acidity, and volume of oxidized indicator, measured portions of a standard solution of potassium dichromate prepared from material of accurately determined oxidizing power were taken, treated with a definite volume of sulfuric, and of hydrofluoric or phosphoric acid, and diluted to the volume specified in Table I. The stated volume of 0.01 M indicator, oxidized, was added and the chromic acid titrated with 0.025 N ferrous sulfate standardized electrometrically against standard ceric sulfate (8), the strength of which had been determined against Bureau of Standards sodium oxalate (8). From the normality of the ferrous sulfate the volume of reducing agent equivalent to the dichromate present was calculated, and the difference between this value and the actual value obtained in the titration, using the indicator, was recorded as the apparent indicator blank.…”

“…of 0.025 N ferrous sulfate per 0.1 cc. of indicator used (8), become 8.15 and 8.11 cc. Two more samples of vanadic acid were treated with 0.3 cc.…”

Determination of Vanadium in Special Alloy Steels

“…The ferrous sulfate used in the analyses in Table II was standardized electrometrically against standard ceric sulfate (11) whose strength had been determined electrometrically against Bureau of Standards sodium oxalate (11). Since dichromate is the primary standard more commonly used in this standardization and since its oxidizing power toward ferrous sulfate has been shown to vary considerably with dilution (1, 9), it seemed important to determine the correct conditions under which to standardize ferrous sulfate for vanadio acid titrations.…”