Book Review:The Ethical Approach to Theism. G. F. Barbour

Precise Determination of Plutonium by Potentiometric Titration

“…Cerium(IV) interference was eliminated by adding a few drops of hydrogen peroxide to reduce the cerium before the fuming operation. In the absence of sulfuric or phosphoric acid, perchloric acid does not oxidize cerium (III) (17).…”

Determination of Cerium and Chromium in Cerium-Chromium-Uranium Mixtures

“…The necessary conditions, as found by the authors and reported by others (12,14,18), seem to be the rapid cooling of the sample after oxidation, and the immediate dilution of the sample when cooled sufficiently. The authors believe the low results often obtained for chromium following a perchloric acid oxidation are caused by reduction of chromium(VI) by chloride ion in the concentrated perchloric acid medium.…”

“…The oxidation methods usually employed, such as a sodium peroxide fusion or oxidation in acid solution with sodium bismuthate or ammonium peroxydisulfate in the presence of silver nitrate (3), result in the oxidation of both cerium and chromium. Perchloric acid has been used to oxidize chromium, but does not oxidize cerium unless mixed with sulfuric or phosphoric acid (12). It would seem possible then to use the peroxydisulfate-silver nitrate oxidation to determine the total amount of cerium and chromium, and the perchloric acid oxidation to determine the chromium alone.…”

“…Lundell, Hoffman, and Bright (7) in a study of perchloric acid oxidation of chromium reported that results were invariably low for chromium, but with special precautions the amount of chromium oxidized could be increased. Smith (12) attributed the apparently incomplete oxidation of chromium to the simultaneous oxidizing and reducing properties of hot concentrated perchloric acid: 4HCIO4 -^2C12 -f-702 -j-2H20 2HCIO4 -^Cl2 + 30-+ H202 Smith (12) reported that the first reaction was by far the more important, but that the second occurred simultaneously and the hydrogen peroxide formed by the reaction reduced part of the chromium.…”