光度滴定法による薬品分析法の研究 (第3報)

ヨウ化物の光度滴定法についての考察

抄録

Photometric titration of potassium iodide at 290mμ was found to give different equivalence according to the acid added.
1) When titrated with potassium permanganate, 2cc. of 0.001M KI corresponds to 1cc. of 0.002M KMnO₄ in sulfuric, phosphoric, and acetic acidity, while a breaking point is present at the point of 1cc. 0.001M KI≡1cc. 0.002N KMnO₄ in hydrochloric acidity.
2) When titrated with potassium iodate, the breaking point is present at the point of 5cc. 0.001M KI≡1cc. 0.001M KIO₃ in sulfuric and phosphoric acidity, and at the point of 0.001M KI≡1cc. 0.001M KIO₃ in hydrochloric acidity.
However, the determined values comes out lower when titration is carried out in hydrochloric acidity. It is therefore considered to be the most suitable to carry out titration with potassium permanganate in sulfuric acidity in determination of potassium iodide in the presence of chloride, bromide, and iodide ions, and with potassium iodate in sulfuric acidity when determining potassium iodide in the presence of chlorine and bromine ions, iodine, and Ethanol