Introducing the primary pH-metric standardization in nonaqueous solvents of extremely high permittivities: behaviour of the potassium hydrogen phthalate buffer in formamide, and acquisition of an appropriate salt bridge for pH measurements

The primary pH-metric standardization, in compliance with the IUPAC guidelines is, for the 1st time, introduced in the domain of nonaq. media of extremely high permittivities. In this context the primary std. pHPS values for the K H phthalate buffer in formamide were detd. over a range of temps., based on the p.d. measurements of Harned's cell. The found pHPS values decrease slightly with increasing temp. in the range 283-323 K according to: pHPS = 7.9538-0.008093 × (T (K)) + 0.0000100 × (T2 (K)). Also, to make the operational cell for pH measurements applicable to the present medium, a suitable equitransferent salt bridge (NH4Cl in formamide) was characterized by the method of the concn. cell with transference.