Open AccessLa formación de precipitados bajo el efecto de la acidez en el método de Mohr
Author(s) -
Kenia Chávez-Ramos,
Dalia Bonilla-Martínez
Publication year - 2014
Publication title -
educación química
Language(s) - Spanish
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 10
eISSN - 1870-8404
pISSN - 0187-893X
DOI - 10.1016/s0187-893x(14)70064-3
Subject(s) - solubility , saturation (graph theory) , chemistry , aqueous solution , mineralogy , nuclear chemistry , mathematics , combinatorics
The main goal of this study was to demonstrate the importance of acidity on precipitation process of Ag2CrO4 and Ag2O, which can be formed in Mohr's method. This can be explained through the interpretation of a Predominance-Existence Diagram, which shows reliable results of a didactic experiment. The first part of this study consists of identifying two kinds of solids, Ag2CrO4, which is reddish, and Ag2O brownish. The second part shows that acidity affects in speciation of Cr (VI) by changes in the color of the aqueous solution. Finally, it has been demonstrated that pH affects on absence or formation of certain solids. These changes can be explained by a predominance-existence diagram, which is useful to identify a logarithmic curve related with conditional solubility of Ag2CrO4 or Ag2O, the conditional solubility constant, and also concentration of silver at saturation. The finding of minimum solubility — without Ag2O can be formed-justifies that optimal interval pH to titrate on Mohr's method is 7.0