Conductometric titration with indicating resistance--IV: the use of membranes with some organic and inorganic acids as active components, for HCl titration in a highly conducting medium.
Membranes consisting of a methyl polymethacrylate or collodion support containing sparingly soluble inorganic or organic acids can be used for end-point detection in acid-base titrations in high-conductivity media. The collodion + Na(3)[As(Mo(3)O(10))(4)].nH(2)O + Na-Alassion CS membrane is a very good conductometric sensor if given preliminary treatment to form molybdic acid. The conductivity jump with this membrane starts at pH approximately 7 and permits titration of strong acid down to 10(-4)M concentration in highly conducting medium. Similar membranes containing some organic acids such as benzoic, o-chlorobenzoic, and o-phthalic also behave as conductometric sensors, giving a conductivity change at a ph which depends on the dissociation constant of the organic acid used and on the way it interacts with the support and the conducting medium used.
Ghergariu
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Department of Mineralogy, University of Cluj-Napoca, Romania.
Liteanu
C
C