<報文>硫黄の定量法の研究(第3報) : 容量法に就いて

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Effects of acidity and alcohol on and also interference of some salts with the volumetric determination of sulfate were studied. At pH 2.0〜2.4,barium rhodizonate changed its color from red to colorless with an excess of sulfate ion. At pH 3,yellowish tint remained after the end point was passed, and above 4,color changed from red to orange. The change from red to colorless was more distinct than that from red to orange. Titration were, therefore, made at higher acidity. Effect of alcohol was little when the volume of solutions was small. At the volume of 50 ml, about 33 per cent alcoholic solution was found to give satisfactory results. Presence of chlorides made the color of barium rhodizonate vivid. Addition of adequate amount of ammonium chloride or sodium chloride was favourable for titration. But potassium chloride, zinc chloride, aluminum chloride and ferric chloride interfered with the determination. Utilizing ion exchange resins, these interfering cations were successfully removed.
東北大学の論文
1951-10-03