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Chelatometric Titration of Lead with Gallein Indicator
Author(s) -
Sun PengJoung
Publication year - 1961
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.196100020
Subject(s) - chemistry , titration , inorganic chemistry , salt (chemistry) , magenta , nuclear chemistry , organic chemistry , inkwell , composite material , materials science
Two methods using gallein as indicator for the direct titration of lead with disodium salt of EDTA have been developed. In one method, the titration of lead was effected in a weakly acidic medium, using pyridine or hexamethylene‐tetramine as buffer. The optimum p H for the titration was found to be at p H 5.5 to 6.0. Gallein indicator undergoes color change from purplish blue to red. In proceeding the titration within the p H range mentioned above, and in the presence of equimolar concentration of magnesium and alkaline earth metals as well as monovalent cations, no interference was observed. In the other method, the titration of lead was carried out in the presence of Rochelle salt, using ammonia and ammonium chloride buffer to keep the solution at P H 10. Sharp color change from violet to deep magenta red was observed at the end point. Only univalent cations, such as sodium, potassium, lithium, ammonium or silver did not show interference with the titration. The use of some masking agents has also been demonstrated.