훼로시안化 칼리움에 依한 鐵의 微量適定法

Volumetric Determination of a small amount of Iron with Potassium Ferrocyanide

  • 원종훈 (釜山 水産大學 製造學科)
  • Won, Chong-Hun (Department of Marine Products, Pusan Fisheries College)
  • 발행 : 19610700

초록

A titration of a small amount of iron with standard potassium ferrocyanide using potassium thiocyanate as indicator has been studied. A sample solution containing $0.1{\sim}1.0$ mg. $Fe^{3+}$ in 60 ml. is pipeted into 100 ml. Erlenmyer flask and the pH of the solution is adjusted to $1.5{\sim}3.0$ with 0.1 N or 1 N $HNO_3$ and $NH_4OH.$ To this solution one ml. of 1 M KCNS solution as indicator is added. The solution colored by iron thiocyanate complex is titrated with 1/200 M or 1/400 M standard solution of potassium ferrocyanide from a 5 ml. micro-buret. Near the end point, when the color of sample changes from deep red to green, about 20 ml. of ether is added and shake the flask vigorously. The red color is extracted to the ether layer. To settle the ether layer a few drops of ethanol is added and then standard solution is added dropwise and shake vigorously. The end point is reached when the color of the ether layer disappears owing to the quantitative formation of $Fe_4[Fe(CN)_6]_3.$ In this titration, 0.lmg. of $Fe^{3+}$ can be determined within 1.0% of titration error, provided the following optimum conditions, i.e., pH $1.5{\sim}3.0$, final concentration of KCNS indicator; $0.01{\sim}0.02M$, at room temperature. The titration found to be interfered by the presence of slightly soluble salts, stable complex forming ions and the ions which would be reduced by ferrocyanide or oxidized by ferric ion.

키워드

참고문헌

  1. Ind. Eng. Chem., Anal. Ed. v.4 I.M. Kolthoff
  2. 日化 v.81 藤田
  3. Textbook of Quantitative Inorganic Analysis(3rd Ed.) I.M. Kolthoff
  4. Colorimetric Determition of Trace of Metals(2nd Ed.) E.B. Sandell
  5. J. Am. Chem. Soc. v.63 H.E. Bent;C.L. French
  6. Ind. Eng. Chem., Anal. Ed. v.13 J.T. Woods;M.G. Mellon
  7. Spot Tests v.I F. Feigl