Cyanide standard soln. contg. complex cyanide, pref. tetra:cyano-zincate - easily releasing cyanide, which is stable and less toxic than alkali cyanide

摘要

Cyanide standard soln. (I) contains complex cyanide (II). Pref. (II) consists of a complex cyanide of Zn, Ni or Cd, pref. an alkali metal tetracyanozincate. USE/ADVANTAGE - (I) is stable in storage and less toxic than the alkali metal cyanides normally used. The cyanide is in easily released but stable form. In an example, 1.25 g(19.2 mmole) KCN were dissolved in ca. 500 ml. distilled water, than 1.127 g (9.6 mmole) Zn(CN)2 were added and the soln. was made up to 11 with distilled water. The Zn(CN)2 was dissolved by stirring and any undissolved fraction was filtered off. The cyanide content was determined by argentometric titration in alkaline medium, using potentiometric indication with a Ag electrode. 1 ml AgNO3 soln. 0.1 mole/1 = 5.2036 mg CN-. Solns. with definite contents were prepd. from the stock soln. by diluting an aliqu